Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Numerator [Abstract]
Net income	$ 14,939	$ 15,814
Basic earnings per share [Abstract]
Weighted average shares (in shares)	17,712,000	17,671,000
Diluted earnings per share [Abstract]
Effect of dilutive stock options and restricted stock grants (in shares)	11,000	16,000
Adjusted weighted average shares (in shares)	17,723,000	17,687,000
Earnings per share [Abstract]
Basic earnings per share (in dollars per share)	$ 0.84	$ 0.89
Diluted earnings per share (in dollars per share)	$ 0.84	$ 0.89
Options [Member]
Earnings Per Share [Abstract]
Options excluded from diluted calculations (in shares)	0	0