| 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 |
| | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K |
| Net income | 534.7 | 477.9 | 350.1 | 171.5 | 120.4 | 147.8 | 125.0 |
| Depreciation and amortization [+] | 41.2 | 34.3 | 34.1 | 44.7 | 33.2 | 36.9 | 37.3 |
| Depreciation | 32.5 | 33.0 | 32.6 | 27.7 | 19.8 | 25.5 | 20.2 |
| Amortization of intangible assets | 8.7 | 1.3 | 1.5 | 16.9 | 13.4 | 11.4 | 17.1 |
| Stock-based compensation | 89.7 | 66.0 | 69.1 | 52.4 | 49.4 | 20.9 | 12.2 |
| Tax benefit from stock-based compensation | | | | | | -5.3 | -10.8 |
| Deferred taxes | -7.5 | -19.6 | -118.3 | -10.3 | -20.9 | -5.9 | -3.7 |
| Change in working capital [+] | 6.8 | 50.8 | -69.4 | -5.4 | 81.8 | 11.2 | 12.6 |
| Accounts receivable | -17.9 | 17.3 | -51.6 | -10.7 | -20.1 | 2.4 | -3.7 |
| Deferred revenues | | | | | 30.2 | 8.6 | 12.4 |
| Income taxes | -4.4 | 12.8 | -1.0 | 29.6 | 41.8 | 8.1 | 4.8 |
| Other | 29.1 | 20.8 | -16.8 | -24.3 | 29.9 | -8.0 | -1.0 |
| Other operating activities | -6.6 | -6.0 | 55.4 | 6.8 | -10.0 | -31.9 | 2.1 |
| Cash from operations | 658.4 | 603.5 | 321.1 | 259.5 | 253.9 | 173.6 | 174.8 |
| |
| Capital expenditures | -38.8 | -31.0 | -28.8 | -46.1 | -25.2 | -21.8 | -19.8 |
| Purchases of property and equipment | -38.8 | -31.0 | -28.8 | -46.1 | -25.2 | -21.8 | -19.8 |
| Acquisitions | -3.8 | | -0.3 | -0.7 | -610.2 | -114.1 | -32.1 |
| Sales of short-term investments | | | | 11.7 | | | |
| Sales of short-term investments | | | | 11.7 | | | |
| Other cash from investing | 1.1 | -6.8 | 147.3 | 7.9 | -7.9 | -4.4 | |
| Cash from investing | -41.5 | -37.8 | 118.2 | -27.2 | -643.4 | -140.2 | -54.0 |
| |
| Cash dividends paid | | -556.4 | | | -1,022.5 | | |
| Issuance of common stock, net | -216.4 | -133.5 | | | 428.8 | | |
| Option exercises | | 0.0 | 59.4 | 39.4 | | | |
| Financing costs | -5.6 | -1.3 | -12.3 | -7.8 | -17.2 | | |
| Other cash from financing | -126.1 | 39.0 | -376.6 | -29.6 | 946.4 | -20.1 | -105.3 |
| Cash from financing | -336.8 | -649.6 | -423.7 | -61.2 | 369.8 | -20.1 | -105.3 |
| |
| Free cash flow | 619.6 | 572.5 | 292.3 | 213.5 | 228.6 | 151.8 | 155.0 |
| Per share (diluted) | $2.10 | $1.93 | $0.99 | $0.79 | $1.24 | $0.90 | $0.94 |