CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Common Stock Class A Common Stock	Common Stock Class B Common Stock	Common Stock	Additional Paid In Capital. Class A Common Stock	Additional Paid In Capital.	Retained Earnings Class A Common Stock	Retained Earnings Class B Common Stock	Retained Earnings	Accumulated Other Comprehensive Income	Class A Common Stock	Class B Common Stock	Total
Balance at beginning of period at Dec. 31, 2015									$ 2,049
Increase (Decrease) in Stockholders' Equity
Net income												$ 17,735
Net change in accumulated other comprehensive income									1,079			1,079
Balance at end of period at Mar. 31, 2016									3,128
Balance at beginning of period at Dec. 31, 2015									2,049
Balance at end of period at Dec. 31, 2016			$ 4,906		$ 138,192			$ 460,621	687			604,406
Balance (in shares) at Dec. 31, 2016	18,615	2,245
Increase (Decrease) in Stockholders' Equity
Net income								20,017				20,017
Net change in accumulated other comprehensive income									554			554
Dividends declared Common Stock:
Dividends declared Common Stock						$ (3,891)	$ (427)			$ (3,891)	$ (427)
Stock options exercised, net of shares redeemed					33							33
Stock options exercised, net of shares redeemed (in shares)	2
Repurchase of Class A Common Stock	$ (2)			$ (107)		$ (435)				(544)
Repurchase of Class A Common Stock (in shares)	(13)
Conversion of Class B Common Stock to Class A Common Stock (in shares)	2	(2)
Net change in notes receivable on Class A Common Stock				51						51
Deferred director compensation expense - Class A Common Stock				$ 55						$ 55
Deferred director compensation expense - Class A Common Stock (in shares)	5
Stock based compensation expense - performance stock units					132							132
Stock based compensation - restricted stock					215							215
Stock based compensation - restricted stock (in shares)	4
Stock based compensation expense - stock options					63							63
Balance at end of period at Mar. 31, 2017			$ 4,904		$ 138,634			$ 475,885	$ 1,241			$ 620,664
Balance (in shares) at Mar. 31, 2017	18,615	2,243