Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended												12 Months Ended
	Apr. 24, 2018	Dec. 31, 2019		Sep. 30, 2019		Jun. 30, 2019		Mar. 31, 2019		Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Discrete tax expense		$ 23,200								$ 33,100
Asset Impairment Charges		13,666												$ 13,666	$ 3,349	$ 0
Loss Contingency, Estimate of Possible Loss Reduction	$ 15,000													15,000
Revenue		489,044		$ 471,248		$ 481,998		$ 444,736		448,463	$ 434,898	$ 452,707	$ 439,618	1,887,026	1,775,686	1,800,434
Gross profit		232,637		229,587		233,620		233,659	[1]	227,779	222,074	232,551	217,914	929,503	900,318	858,776
Net earnings		$ 1,684	[2]	$ 62,047	[2]	$ 46,118	[2]	$ 61,748	[2]	$ 98,516	$ 73,151	$ 71,563	$ 39,195	$ 171,597	$ 282,425	$ 107,223
Basic earnings per share:
Basic earnings per share (in dollars per share)		$ 0.01		$ 0.46		$ 0.34		$ 0.46		$ 0.72	$ 0.53	$ 0.52	$ 0.28	$ 1.27	$ 2.05	$ 0.78
Diluted earnings per share:
Diluted earnings per share (in dollars per share)		$ 0.01		$ 0.46		$ 0.34		$ 0.45		$ 0.71	$ 0.52	$ 0.51	$ 0.28	$ 1.26	$ 2.01	$ 0.77

[1] (1)

[2]
(2)