Condensed Consolidated Statement of Shareholders' Equity - USD ($) $ in Thousands	Common Stock	Preferred Stock 8% Preferred Stock	Preferred Stock 7% Preferred Stock	Preferred Stock 6% Preferred Stock	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	8% Preferred Stock	7% Preferred Stock	6% Preferred Stock	Total
Balance at beginning of the period at Dec. 31, 2017	$ 134,891				$ 192,008	$ (1,006)	$ 41,581			$ 367,474
Balance at beginning of the period (in shares) at Dec. 31, 2017	28,685,167						41,625
Condensed Consolidated Statements of Shareholders’ Equity
Net income					15,061					15,061
Shares issued for stock compensation plans	$ 50									50
Shares issued for stock compensation plans (in shares)	7,039
Dividends on 8% preferred stock					(833)					(833)
Dividends on common stock					(1,721)					(1,721)
Reclassification of deferred tax asset due to tax reform					243	(243)
Other comprehensive income (loss)						(318)				(318)
Balance at end of the period at Mar. 31, 2018	$ 134,941				204,758	(1,567)	$ 41,581			379,713
Balance at end of the period (in shares) at Mar. 31, 2018	28,692,206						41,625
Balance at beginning of the period at Dec. 31, 2017	$ 134,891				192,008	(1,006)	$ 41,581			367,474
Balance at beginning of the period (in shares) at Dec. 31, 2017	28,685,167						41,625
Condensed Consolidated Statements of Shareholders’ Equity
Net income										47,452
Other comprehensive income (loss)										(48)
Balance at end of the period at Sep. 30, 2018	$ 135,021				232,041	(1,297)	$ 41,581			407,346
Balance at end of the period (in shares) at Sep. 30, 2018	28,694,036						41,625
Balance at beginning of the period at Mar. 31, 2018	$ 134,941				204,758	(1,567)	$ 41,581			379,713
Balance at beginning of the period (in shares) at Mar. 31, 2018	28,692,206						41,625
Condensed Consolidated Statements of Shareholders’ Equity
Net income					15,652					15,652
Shares issued for stock compensation plans	$ 11									11
Shares issued for stock compensation plans (in shares)	1,830
Dividends on 8% preferred stock					(832)					(832)
Dividends on common stock					(1,722)					(1,722)
Other comprehensive income (loss)						97				97
Balance at end of the period at Jun. 30, 2018	$ 134,952				217,856	(1,470)	$ 41,581			392,919
Balance at end of the period (in shares) at Jun. 30, 2018	28,694,036						41,625
Condensed Consolidated Statements of Shareholders’ Equity
Net income					16,739					16,739
Shares issued for stock compensation plans	$ 69									69
Dividends on 8% preferred stock					(833)					(833)
Dividends on common stock					(1,721)					(1,721)
Other comprehensive income (loss)						173				173
Balance at end of the period at Sep. 30, 2018	$ 135,021				232,041	(1,297)	$ 41,581			407,346
Balance at end of the period (in shares) at Sep. 30, 2018	28,694,036						41,625
Balance at beginning of the period at Dec. 31, 2018	$ 135,057	$ 41,581			244,909	(310)				421,237
Balance at beginning of the period (in shares) at Dec. 31, 2018	28,694,036	41,625
Condensed Consolidated Statements of Shareholders’ Equity
Net income					10,570					10,570
Shares issued for stock compensation plans	$ 133									133
Shares issued for stock compensation plans (in shares)	10,127
Issuance of shares			$ 48,269							48,269
Issuance of shares (in shares)			2,000,000
Dividends on 8% preferred stock					(833)					(833)
Dividends on common stock					(2,009)					(2,009)
Other comprehensive income (loss)						464				464
Balance at end of the period at Mar. 31, 2019	$ 135,190	$ 41,581	$ 48,269		252,637	154				477,831
Balance at end of the period (in shares) at Mar. 31, 2019	28,704,163	41,625	2,000,000
Balance at beginning of the period at Dec. 31, 2018	$ 135,057	$ 41,581			244,909	(310)				421,237
Balance at beginning of the period (in shares) at Dec. 31, 2018	28,694,036	41,625
Condensed Consolidated Statements of Shareholders’ Equity
Net income										47,268
Other comprehensive income (loss)										1,002
Balance at end of the period at Sep. 30, 2019	$ 135,507	$ 41,581	$ 50,245	$ 120,863	280,551	692				629,439
Balance at end of the period (in shares) at Sep. 30, 2019	28,706,438	41,625	2,081,800	125,000
Balance at beginning of the period at Mar. 31, 2019	$ 135,190	$ 41,581	$ 48,269		252,637	154				477,831
Balance at beginning of the period (in shares) at Mar. 31, 2019	28,704,163	41,625	2,000,000
Condensed Consolidated Statements of Shareholders’ Equity
Net income					16,439					16,439
Shares issued for stock compensation plans	$ 184									184
Shares issued for stock compensation plans (in shares)	2,275
Issuance of shares			$ 23,826							23,826
Issuance of shares (in shares)			955,800
Dividends on 8% preferred stock					(832)					(832)
Dividends on 7% preferred stock					(911)					(911)
Dividends on common stock					(2,010)					(2,010)
Other comprehensive income (loss)						486				486
Balance at end of the period at Jun. 30, 2019	$ 135,374	$ 41,581	$ 72,095		265,323	640				515,013
Balance at end of the period (in shares) at Jun. 30, 2019	28,706,438	41,625	2,955,800
Condensed Consolidated Statements of Shareholders’ Equity
Net income					20,259					20,259
Shares issued for stock compensation plans	$ 133									133
Issuance of shares				$ 120,863					$ 120,863
Issuance of shares (in shares)				125,000
Repurchase of Preferred Stock			$ (21,850)					$ (21,850)
Repurchase of Preferred Stock (in shares)			(874,000)
Dividends on 8% preferred stock					(833)					(833)
Dividends on 7% preferred stock					(1,293)					(1,293)
Dividends on 6% preferred stock					(896)					(896)
Dividends on common stock					(2,009)					(2,009)
Other comprehensive income (loss)						52				52
Balance at end of the period at Sep. 30, 2019	$ 135,507	$ 41,581	$ 50,245	$ 120,863	$ 280,551	$ 692				$ 629,439
Balance at end of the period (in shares) at Sep. 30, 2019	28,706,438	41,625	2,081,800	125,000