Net Income Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	6,462	0	5,908	1,548
Net Income	$ 22,833	$ 31,054	$ 53,831	$ 35,929
Weighted average number of common shares outstanding (for basic calculation)	20,622,000	20,352,000	20,577,000	20,304,000
Dilutive securities	898,000	1,217,000	969,000	1,232,000
Diluted (in shares)	21,520,000	21,569,000	21,546,000	21,536,000
EPS - basic	$ 1.11	$ 1.53	$ 2.62	$ 1.77
Diluted (In dollars per share)	$ 1.06	$ 1.44	$ 2.50	$ 1.67