Stock Repurchases (Details) - USD ($) shares in Millions		1 Months Ended	3 Months Ended		6 Months Ended
	Feb. 10, 2016	Jul. 18, 2016	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Jul. 16, 2016
Stockholders' Equity Note [Abstract]
Stock repurchase program, authorized amount			$ 1,400,000,000		$ 1,400,000,000
Stock repurchase program, remaining authorized amount			196,200,000		$ 196,200,000
Accelerated share repurchases, initial price to be paid	$ 200,000,000
Subsequent Event [Line Items]
Accelerated share repurchases, number of shares	1.3
Accelerated share repurchases, percentage of shares to be repurchased	75.00%
Shares repurchased from employees who surrendered shares to satisfy minimum tax withholding obligations					0.2
Shares repurchased from employees who surrendered shares to satisfy minimum tax withholding obligations, value			$ 21,400,000	$ 21,800,000	$ 21,400,000	$ 21,800,000
Subsequent Event [Member]
Stockholders' Equity Note [Abstract]
Stock repurchase program, authorized amount							$ 100,000,000
Subsequent Event [Line Items]
Accelerated share repurchases, number of shares		0.2