Stock Repurchase (Narrative) (Details) - USD ($)	1 Months Ended						6 Months Ended
	Jun. 30, 2016	May 31, 2016	Apr. 30, 2016	Mar. 31, 2016	Feb. 29, 2016	Jan. 31, 2016	Jun. 30, 2016	Sep. 09, 2015	Nov. 15, 2013
Class of Stock Disclosures [Abstract]
Stock repurchase, additional authorized amount (up to)								$ 750,000,000	$ 600,000,000
Number of shares repurchased (in shares)	439,031	845,869	1,033,098	1,405,025	869,898	1,147,337	5,740,258
Shares repurchased, value							$ 451,697,000
Value remaining under total repurchase authorization	$ 500,406,000						$ 500,406,000