| In millions, except per share items | Dec-31-21 | Dec-31-20 | Dec-31-19 | Dec-31-18 | Dec-31-17 | Dec-31-16 | Dec-31-15 | Dec-31-14 |
| | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K |
| Net income | 270.2 | 121.2 | 274.8 | 366.3 | 300.3 | 275.5 | 193.6 | 88.9 |
| Depreciation and amortization | 327.2 | 335.6 | 332.4 | 352.2 | 375.0 | 387.3 | 417.9 | 442.2 |
| Asset impairment charges | 1.9 | 19.6 | 24.4 | 53.3 | 40.1 | 5.2 | 1.0 | |
| Stock-based compensation | 17.1 | 11.0 | 12.7 | 9.4 | 10.5 | 11.6 | 23.3 | 9.5 |
| Change in working capital [+] | 14.5 | -8.2 | -24.4 | -11.5 | -17.8 | -4.1 | -1.1 | -1.1 |
| Restricted cash | | | | | | | | 16.9 |
| Accounts receivable | 2.2 | -9.8 | -27.0 | -12.3 | -26.5 | 1.6 | 1.8 | -5.3 |
| Other | 12.3 | 1.6 | 2.6 | 0.8 | 8.7 | -5.7 | -2.9 | -12.7 |
| Other operating activities | -78.6 | -35.9 | -91.2 | -228.0 | -156.2 | -107.9 | -110.7 | -60.2 |
| Cash from operations | 552.2 | 443.1 | 528.7 | 541.7 | 551.9 | 567.5 | 524.0 | 479.2 |
| |
| Capital expenditures | -308.6 | -284.8 | -395.1 | -268.7 | -202.9 | -192.4 | -189.9 | -214.7 |
| Purchases of property and equipment | -308.6 | -284.8 | -395.1 | -268.7 | -202.9 | -192.4 | -189.9 | -214.7 |
| Sales of short-term investments, net [+] | -1.0 | -1.5 | 12.5 | -2.2 | -2.6 | -2.7 | 51.4 | 8.9 |
| Purchases of short-term investments | -17.5 | -22.6 | -37.8 | -33.1 | -28.3 | -46.3 | -24.3 | -23.1 |
| Sales of short-term investments | 16.4 | 21.1 | 50.3 | 30.9 | 25.6 | 43.6 | 75.7 | 32.0 |
| Other cash from investing | -21.4 | 119.0 | 210.5 | 940.5 | 152.6 | 53.2 | -52.2 | 4.9 |
| Cash from investing | -331.0 | -167.2 | -172.1 | 669.6 | -52.9 | -141.9 | -190.7 | -200.8 |
| |
| Cash dividends paid | -257.2 | -170.4 | -334.9 | -333.4 | -317.4 | -295.2 | -268.3 | -173.1 |
| Repurchase of common stock, net | 5.1 | -25.0 | -14.6 | -104.7 | -5.9 | | | |
| Financing costs | -33.7 | -34.7 | -7.3 | -56.6 | -11.1 | -17.7 | -10.8 | -3.0 |
| Other cash from financing | -75.2 | 233.4 | -43.7 | -889.8 | -179.0 | -156.2 | -78.6 | -161.5 |
| Cash from financing | -293.6 | 72.7 | -385.9 | -1,271.3 | -491.2 | -433.7 | -336.0 | -331.7 |
| |
| Free cash flow | 243.7 | 158.3 | 133.6 | 273.0 | 349.1 | 375.1 | 334.1 | 264.5 |
| Per share (diluted) | $0.82 | $0.53 | $0.45 | $0.90 | $1.14 | $1.23 | $1.10 | $1.08 |
| |
| Cash paid for interest | 191.0 | 183.2 | 178.9 | 212.9 | 223.2 | 228.4 | 244.1 | 282.6 |