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, 2016					$ (1,497.6)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 375.0
Other comprehensive income (loss), net of tax	270.5
Ending balance at Mar. 31, 2017					(1,227.1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative-effect adjustment | ASU 2014-09	52.0					$ 52.0
Cumulative-effect adjustment | ASU 2016-01	67.9					67.9
Cumulative-effect adjustment | ASU 2016-06	7.5					7.5
Beginning balance at Dec. 31, 2017	$ 36,176.4	$ 81.6	$ 25,082.2	$ (283.0)	1,375.0	9,920.6
Beginning balance (in shares) at Dec. 31, 2017	917.1	917.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 550.6
Other comprehensive income (loss), net of tax	471.1				471.1
Shares issued under employee benefit plans and other (in shares)		1.8
Shares issued under employee benefit plans and other	33.5	$ 0.1	33.4
Share-based compensation	41.0		41.0
Shares released by employee benefit trust to satisfy exercise of stock options				3.9		(3.9)
Ending balance at Mar. 31, 2018	$ 37,400.0	$ 81.7	$ 25,156.6	$ (279.1)	$ 1,846.1	$ 10,594.7
Ending balance (in shares) at Mar. 31, 2018	918.9	918.9