Income Taxes - Income Taxes from Continuing Operations (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings from continuing operations before income taxes:
United States									$ 356,644	$ 254,355	$ 344,614
Foreign									17,217	60,190	62,642
Earnings from continuing operations before income taxes	$ 111,338	$ 116,140	$ 98,283	$ 48,100	$ 78,577	$ 94,492	$ 80,854	$ 60,622	373,861	314,545	407,256
Current tax (benefit) expense from continuing operations:
Federal									(23,333)	6,752	2,731
State									6,862	9,360	7,713
Foreign									10,123	6,442	6,411
Total									(6,348)	22,554	16,855
Deferred tax expense (benefit) from continuing operations:
Federal									110,408	(510,172)	106,718
State									313	8,080	16,299
Foreign									(6,119)	1,794	2,152
Total									104,602	(500,298)	125,169
Provision for (benefit from) income taxes from continuing operations									98,254	$ (477,744)	$ 142,024
Alternative minimum tax refunds, net of sequestration charge									$ 22,000