Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2020		Sep. 30, 2020		Jun. 30, 2020		Mar. 31, 2020		Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Discrete tax expense	$ 18,300								$ 24,400
Asset Impairment Charges									13,700				$ 0	$ 13,666	$ 3,349
Loss Contingency, Estimate of Possible Loss Reduction													15,000
Revenue	524,337		$ 466,414		$ 482,015		$ 450,923		489,044	$ 471,248	$ 481,998	$ 444,736	1,923,689	1,887,026	1,775,686
Gross profit	246,531		228,914		252,200		219,368	[1]	232,370	229,747	233,408	233,861	947,013	929,386	901,223
Net earnings	$ 75,240	[2]	$ 60,663	[2]	$ 61,257	[2]	$ 15,424	[2]	$ 1,684	$ 62,047	$ 46,118	$ 61,748	$ 212,584	$ 171,597	$ 282,425
Basic earnings per share:
Basic earnings per share (in dollars per share)	$ 0.57		$ 0.46		$ 0.47		$ 0.12		$ 0.01	$ 0.46	$ 0.34	$ 0.46	$ 1.61	$ 1.27	$ 2.05
Diluted earnings per share:
Diluted earnings per share (in dollars per share)	$ 0.57		$ 0.46		$ 0.47		$ 0.11		$ 0.01	$ 0.46	$ 0.34	$ 0.45	$ 1.60	$ 1.26	$ 2.01
Gain (Loss) on Extinguishment of Debt													$ (9,126)	$ 0	$ 0

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