Shareholders' Equity Repurchase Program (Details) - USD ($)	Jan. 06, 2016	Dec. 31, 2015	Aug. 11, 2015	Jul. 20, 2015	Dec. 31, 2014	Jul. 21, 2014	Jun. 30, 2014
Accelerated Share Repurchases [Line Items]
Treasury Stock, Shares		7,430,000	3,059,629		2,385,000
Stock Repurchase Program, Number of Shares Authorized to be Repurchased			50,000,000
Stock Repurchase Program, Authorized Amount		$ 100,000,000		$ 400,000,000			$ 25,000,000
Maximum
Accelerated Share Repurchases [Line Items]
Stock Repurchase Program, Authorized Amount				$ 450,000,000		$ 200,000,000
Third Accelerated Share Repurchase Agreement [Member]
Accelerated Share Repurchases [Line Items]
Treasury Stock, Shares	363,209
Stock Repurchase Program, Authorized Amount	$ 375,000,000