Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Common Stock [Member]
Numerator [Abstract]
Distributed earnings									$ 13,913	$ 32,595	$ 10,473
Undistributed earnings									6,284	(4,741)	8,896
Basic									20,197	27,854	19,369
Class A Common earnings									1,668	2,453	1,706
Diluted									$ 21,865	$ 30,307	$ 21,075
Denominator [Abstract]
Weighted average shares outstanding - basic (in shares)									18,360	19,182	19,381
Assumed conversion of Class A Common Stock (in shares)									1,611	1,765	1,801
Dilutive options, awards and common stock equivalents (in shares)									290	348	417
Total weighted average diluted Common Stock (in shares)									20,261	21,295	21,599
Basic net earnings per share [Abstract]
Common stock (in dollars per share)	$ 0.32	$ 0.31	$ 0.30	$ 0.18	$ 0.46	$ 0.40	$ 0.30	$ 0.30	$ 1.10	$ 1.45	$ 1.00
Diluted net earnings per share [Abstract]
Common stock (in dollars per share)	0.31	0.31	0.29	0.17	0.45	0.39	0.29	0.29	$ 1.08	$ 1.42	$ 0.98
Class A Common Stock [Member]
Numerator [Abstract]
Distributed earnings									$ 1,143	$ 2,869	$ 919
Undistributed earnings									525	(416)	787
Class A Common earnings									$ 1,668	$ 2,453	$ 1,706
Denominator [Abstract]
Weighted average shares outstanding (in shares)									1,611	1,765	1,801
Basic net earnings per share [Abstract]
Common stock (in dollars per share)	0.30	0.30	0.28	0.17	0.44	0.38	0.28	0.28	$ 1.04	$ 1.39	$ 0.95
Diluted net earnings per share [Abstract]
Common stock (in dollars per share)	$ 0.30	$ 0.30	$ 0.27	$ 0.17	$ 0.45	$ 0.38	$ 0.28	$ 0.28	$ 1.03	$ 1.39	$ 0.94