Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Earnings Per Share [Abstract]
Net income as reported	$ 22,251	$ 11,955	$ 43,172	$ 24,346
Weighted average common shares outstanding (in shares)	23,124,000	23,475,000	23,119,000	22,706,000
Additional dilutive common stock equivalents (in shares)	194,000	257,000	213,000	314,000
Weighted average diluted common shares outstanding (in shares)	23,318,000	23,732,000	23,332,000	23,020,000
Basic earnings per common share (in dollars per share)	$ 0.96	$ 0.51	$ 1.87	$ 1.07
Diluted earnings per common share (in dollars per share)	$ 0.95	$ 0.50	$ 1.85	$ 1.06
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount			0	0