Equity - Authorized Shares for Issuance - USD ($) $ / shares in Units, $ in Millions		1 Months Ended	12 Months Ended
	Jan. 31, 2015	Jan. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Jan. 31, 2016	Jul. 31, 2015	Jun. 30, 2015	May. 20, 2015	May. 19, 2015	Jul. 31, 2014	Jun. 30, 2014
Stock-Based Compensation:
Common stock shares authorized			1,000,000,000	500,000,000					1,000,000,000	500,000,000
Quarterly dividend approved by Board prior to payment, per share (in dollars per share)							$ 0.14	$ 0.125			$ 0.125	$ 0.10
Dividends declared			$ 163.7	$ 140.6	$ 96.8
Dividends paid			$ 159.3	$ 101.9	$ 96.8
2013 Stock Repurchase Program
Stock-Based Compensation:
Number of shares authorized to be repurchased under the current open-market stock repurchase program	20,000,000	20,000,000
Repurchase of stock program, period	2 years
Number of shares repurchased under the current open-market stock repurchase program				11,428,610
Payments for shares repurchased under the current open-market stock repurchase program (in dollars)				$ 539.4
2015 Stock Repurchase Program
Stock-Based Compensation:
Number of shares authorized to be repurchased under the current open-market stock repurchase program	10,000,000	10,000,000
Repurchase of stock program, period		2 years
Number of shares repurchased under the current open-market stock repurchase program			4,500,000
Payments for shares repurchased under the current open-market stock repurchase program (in dollars)			$ 248.9
Number of shares remaining that maybe repurchased under the stock repurchase program						5,500,000