Share Repurchases and Dividends (Details) - USD ($)	1 Months Ended	12 Months Ended
	Oct. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Stockholders' Equity Note [Abstract]
Number of shares repurchased (in shares)		10,700,000	9,600,000
Amount paid		$ 736,900,000	$ 610,700,000
Weighted average cost per share (in dollars per share)		$ 69.06	$ 63.84
Shares pending settlement (in shares)		0
Shares adding to existing share repurchase program	$ 2,000,000,000.0
Remaining authorized purchase capacity		$ 1,100,000,000
Quarterly dividend per share (in dollars per share)	$ 0.375	$ 1.44	$ 1.33	$ 1.24
Cash dividends declared		$ 468,400,000	$ 446,300,000	$ 423,800,000
Quarterly dividend payable		$ 121,000,000.0	$ 114,400,000