Subsequent Events - Additional Information (Details) - USD ($) shares in Thousands, $ in Thousands	1 Months Ended	12 Months Ended
	Jan. 29, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Subsequent Event [Line Items]
Common stock repurchased, value		$ 2,015,947	$ 2,472,645	$ 1,764,969
Common Stock [Member]
Subsequent Event [Line Items]
Common stock repurchased, value		$ 0	$ 0	$ 0
Subsequent Event [Member] | Common Stock [Member] | Open Market And Privately Negotiated Repurchases [Member]
Subsequent Event [Line Items]
Common stock repurchased (in shares)	51,883
Common stock repurchased, value	$ 194,127