Stock Repurchase (Narrative) (Details) - USD ($)	1 Months Ended												12 Months Ended
	Dec. 31, 2015	Nov. 30, 2015	Oct. 31, 2015	Sep. 30, 2015	Aug. 31, 2015	Jul. 31, 2015	Jun. 30, 2015	May. 31, 2015	Apr. 30, 2015	Mar. 31, 2015	Feb. 28, 2015	Jan. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Sep. 09, 2015	Nov. 15, 2013
Class of Stock Disclosures [Abstract]
Outstanding common stock repurchase authorized, value																$ 750,000,000	$ 600,000,000
Number of shares repurchased	0	0	924,960	0	67,436	303,807	482,586	472,000	640,000	645,000	120,000	529,100	4,184,889	3,298,490	7,707,014
Shares repurchased, value													$ 284,567,000
Value remaining under total repurchase authorization	$ 952,103,000												$ 952,103,000