Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income per share
Strike price of the warrant transactions (in dollars per share)	$ 80.9063
Numerator, dollars in thousands:
Net earnings	$ 126,950	$ 113,056	$ 110,993
Denominator:
Weighted average shares outstanding, basic (in shares)	52,615,269	52,412,181	51,989,824
Effect of dilutive securities:
Stock options, RSUs, and SARs (in shares)	1,074,474	1,404,573	2,109,048
Weighted average shares outstanding, diluted (in shares)	53,689,743	53,816,754	54,098,872
Earnings per share, basic (in dollars per share)	$ 2.41	$ 2.16	$ 2.13
Earnings per share, diluted (in dollars per share)	$ 2.36	$ 2.10	$ 2.05
Stock options, RSUs, PSUs
Income per share
Common stock equivalents excluded in the calculation of diluted income per share (in shares)	2,888,785	1,145,446	199,982
Convertible Debt
Income per share
Conversion price (in dollars per share)	$ 59.33