Consolidated Statement of Changes in Equity - USD ($) shares in Millions, $ in Millions	Total	Common stock	Additional paid-in capital	Treasury stock	Accumulated other comprehensive (loss)/income	Retained earnings
Beginning balance at Dec. 31, 2015					$ (183.8)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ (129.9)
Other comprehensive income, net of tax					49.6
Dividends	(130.2)
Ending balance at Sep. 30, 2016					(134.2)
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	$ 1,166.1					1,166.1
Other comprehensive income, net of tax	2,466.7				2,466.7
Shares issued under employee benefit plans and other (in shares)		3.7
Shares issued under employee benefit plans and other	109.8	$ 0.2	109.6
Share-based compensation	159.7		159.7
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 Sep. 30, 2017	$ 32,654.6	$ 81.5	$ 25,020.9	$ (283.0)	$ 969.1	$ 6,866.1
Ending balance (in shares) at Sep. 30, 2017	915.9	915.9