Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Sep. 30, 2018	Mar. 31, 2018
Income per share
Strike price of the warrant transactions (in dollars per share)			$ 80.9063	$ 80.9063
Common stock equivalents excluded in the calculation of diluted income per share (in shares)	3,034,099	608,948
Numerator, dollars in thousands:
Net earnings	$ 21,518	$ 18,340
Denominator:
Weighted average shares outstanding, basic (in shares)	52,534,787	52,336,443
Effect of dilutive securities:
Stock options, PSU, RSU and SAR (in shares)	1,046,264	1,648,942
Weighted average shares outstanding, diluted (in shares)	53,581,051	53,985,385
Earnings per share, basic (in dollars per share)	$ 0.41	$ 0.35
Earnings per share, diluted (in dollars per share)	$ 0.40	$ 0.34
2023 Notes
Income per share
Conversion price, per share of common stock (in dollars per share)			$ 59.33	$ 59.33