Consolidated Statement of Changes in Equity - USD ($) shares in Millions, $ in Millions	Total	Common stock	Additional paid-in capital	Treasury stock	Accumulated other comprehensive income	Retained earnings
Beginning balance at Dec. 31, 2015					$ (183.8)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 256.9
Other comprehensive income net of tax					(202.0)
Ending balance at Jun. 30, 2016					(385.8)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative-effect adjustment from adoption of ASU 2016-09	39.0		$ 10.7			$ 28.3
Beginning balance at Dec. 31, 2016	$ 28,948.0	$ 81.3	24,740.9	$ (301.9)	(1,497.6)	5,925.3
Beginning balance (in shares) at Dec. 31, 2016	912.2	912.2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 615.3					615.3
Other comprehensive income net of tax	1,697.7				1,697.7
Shares issued under employee benefit plans and other (in shares)		3.1
Shares issued under employee benefit plans and other	93.4	$ 0.2	93.2
Share-based compensation	106.4		106.4
Shares released by employee benefit trust to satisfy exercise of stock options	0.0			18.9		(18.9)
Dividends	(234.7)					(234.7)
Ending balance at Jun. 30, 2017	$ 31,265.1	$ 81.5	$ 24,951.2	$ (283.0)	$ 200.1	$ 6,315.3
Ending balance (in shares) at Jun. 30, 2017	915.3	915.3