| In millions, except per share items | Dec-31-19 | Dec-31-18 | Dec-31-17 | Dec-31-16 | Dec-31-15 | Dec-31-14 | Dec-31-13 | Dec-31-12 |
| | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K |
| Net income | 245.8 | 394.1 | 406.1 | 223.0 | 275.2 | 291.5 | 653.2 | 302.0 |
| Depreciation and amortization [+] | 123.6 | 124.7 | 107.1 | 98.0 | 96.7 | 101.6 | 85.2 | 76.9 |
| Depreciation | 95.1 | 95.8 | 84.8 | 76.0 | 77.5 | 81.7 | 74.6 | 65.6 |
| Amortization of intangible assets | 28.5 | 28.9 | 22.3 | 22.0 | 19.2 | 19.9 | 10.6 | 11.3 |
| Asset impairment charges | | | | | 8.1 | | | |
| Stock-based compensation | 9.2 | 20.0 | 16.4 | 13.1 | 12.0 | 15.5 | 13.6 | 14.3 |
| Deferred taxes | -19.4 | -23.6 | -48.2 | 68.3 | -11.7 | 4.5 | -64.6 | -2.9 |
| Change in working capital [+] | 20.5 | -124.5 | 68.3 | -45.1 | -13.2 | -170.5 | -33.8 | 50.5 |
| Accounts receivable | 79.2 | 27.5 | -64.3 | -61.5 | -41.8 | -123.9 | -44.3 | -6.2 |
| Inventories | 21.2 | -13.4 | -16.0 | -3.9 | -42.7 | -2.5 | -16.0 | 5.7 |
| Accounts payable | -43.2 | -23.8 | 5.4 | 21.7 | 52.1 | -18.3 | 33.1 | -23.0 |
| Other | -36.7 | -114.8 | 143.2 | -1.4 | 19.2 | -25.8 | -6.6 | 74.0 |
| Other operating activities | 60.2 | 77.8 | -128.2 | 48.1 | 33.2 | 71.8 | 12.2 | -82.5 |
| Cash from operations | 439.9 | 468.5 | 421.5 | 405.4 | 400.3 | 314.4 | 665.8 | 358.3 |
| |
| Capital expenditures [+] | -153.6 | -132.1 | -110.5 | -114.0 | -101.2 | -135.9 | -121.5 | -100.5 |
| Purchases of property and equipment | -144.8 | -118.2 | -104.7 | -104.0 | -90.3 | -123.8 | -108.1 | -91.7 |
| Capitalized product costs | -8.8 | -13.9 | -5.8 | -10.0 | -10.9 | -12.1 | -13.4 | -8.8 |
| Sales of property and equipment | | | | 7.0 | 0.6 | | | |
| Purchases of short-term investments, net | 145.4 | -102.0 | 13.2 | -51.6 | -81.6 | | | |
| Purchases of short-term investments | -746.5 | -687.2 | -535.2 | -324.6 | -121.4 | | | |
| Sales of short-term investments | 891.9 | 585.2 | 548.4 | 273.0 | 39.8 | | | |
| Other cash from investing | -2.2 | -12.4 | -390.9 | -93.2 | -20.0 | -75.2 | -55.2 | -5.1 |
| Cash from investing | -10.4 | -246.5 | -488.2 | -251.8 | -202.2 | -211.1 | -176.7 | -105.6 |
| |
| Repurchase of common stock, net | -30.6 | -300.0 | -120.0 | -250.0 | -249.2 | -351.5 | -243.2 | -198.3 |
| Option exercises | 1.2 | 0.6 | 9.5 | 3.9 | 17.3 | 15.0 | 49.7 | 28.6 |
| Other cash from financing | -7.2 | -526.5 | 390.1 | 474.5 | 212.5 | 245.1 | 99.5 | 44.3 |
| Cash from financing | -39.0 | -827.1 | 260.6 | 220.6 | -54.0 | -121.4 | -193.4 | -182.6 |
| |
| Free cash flow | 295.1 | 350.3 | 316.8 | 301.4 | 310.0 | 190.6 | 557.7 | 266.6 |
| Per share (diluted) | $5.57 | $6.34 | $5.74 | $5.21 | $5.13 | $2.95 | $8.59 | $3.95 |
| |
| Cash paid for interest | 9.2 | 20.0 | 20.0 | 16.5 | 10.1 | 2.0 | 0.3 | 1.1 |
| Cash paid for income taxes | 89.1 | 109.0 | 64.1 | 50.8 | 49.4 | 48.4 | 45.2 | 30.3 |