Income Taxes Income Taxes Details 1 (Details) - USD ($) $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2017	[1]	Sep. 30, 2017	[1]	Jun. 30, 2017	[1]	Mar. 31, 2017	[1]	Dec. 31, 2016	[1]	Sep. 30, 2016	[1]	Jun. 30, 2016	[1]	Mar. 31, 2016	[1]	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Taxes [Abstract]
United States																	$ 347,680	$ 287,946	$ 331,622
Foreign																	52,578	38,712	38,729
Income from continuing operations before income taxes	$ 133,636		$ 66,578		$ 101,518		$ 98,526		$ 139,289		$ 74,963		$ 32,639		$ 79,767		$ 400,258	$ 326,658	$ 370,351

[1] Includes Gains (losses) on divestitures and impairment charges, net, as described in Note 16.