Income Taxes Income Taxes Details 1 (Details) - USD ($) $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2018	[1]	Sep. 30, 2018	[1]	Jun. 30, 2018	[1]	Mar. 31, 2018	[1]	Dec. 31, 2017	[1]	Sep. 30, 2017	[1]	Jun. 30, 2017	[1]	Mar. 31, 2017	[1]	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Taxes [Abstract]
United States																	$ 399,123	$ 347,680	$ 287,946
Foreign																	42,609	52,578	38,712
Income before income taxes	$ 126,012		$ 86,036		$ 119,315		$ 110,369		$ 133,636		$ 66,578		$ 101,518		$ 98,526		$ 441,732	$ 400,258	$ 326,658

[1] Includes Gains (losses) on divestitures and impairment charges, net, as described in Note 15.