Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Class A Common Stock	Class B Common Stock	Preferred Stock	Common Stock	Common Stock Class A Common Stock	Common Stock Class B Common Stock	Additional Paid- in Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income (Loss)
Beginning Balance at Dec. 31, 2014	$ 503,315			$ 79,877		$ 358	$ 6	$ 422,910	$ 29,589	$ (29,798)	$ 373
Comprehensive income:
Net income	43,034	$ 43,018	$ 16						43,034
Other comprehensive income, net	1,212										1,212
Issuance of stock				110,873	$ 0	36	(6)	(30)
Exercise of stock options	465							(263)		728
Stock option compensation expense	357							357
Restricted stock compensation expense	6,285							6,285
Stock appreciation right expense	188							188
Restricted stock surrendered due to employee tax liability	(1,810)					(1)		(1,809)
Tax effect from stock compensation plan	(187)							(187)
Shares purchased under the Dividend Reinvestment Plan	(2)							148	(150)
Stock appreciation right dividend equivalents	(528)								(528)
Dividends declared	(12,875)								(12,875)
Preferred stock dividends	(6,793)								(6,793)
Ending Balance at Sep. 30, 2015	643,534			190,750		393	0	427,599	52,277	(29,070)	1,585
Beginning Balance at Dec. 31, 2015	652,405			190,750		395	1	429,790	63,534	(29,070)	(2,995)
Comprehensive income:
Net income	82,152	$ 81,963	$ 189						82,152
Other comprehensive income, net	10,060										10,060
Issuance of stock				120,255	$ 175,090	118	1	174,971
Redemption of preferred stock	(42,000)			(41,934)					(66)
Issuance of common stock for Stock Employee Compensation Trust	0					25		(25)		0
Exercise of stock options	(359)							(359)
Stock option compensation expense	400							400
Restricted stock compensation expense	8,110							8,110
Stock appreciation right expense	17							17
Restricted stock surrendered due to employee tax liability	(3,886)					(2)		(3,884)
Tax effect from stock compensation plan	1,877							1,877
Shares purchased under the Dividend Reinvestment Plan	(2)							172	(174)
Stock appreciation right dividend equivalents	(558)								(558)
Dividends declared	(17,336)								(17,336)
Preferred stock dividends	(14,801)								(14,801)
Ending Balance at Sep. 30, 2016	$ 971,424			$ 269,071		$ 536	$ 2	$ 611,069	$ 112,751	$ (29,070)	$ 7,065