Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands		Stockholders' Equity, Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Other Comprehensive Income (Loss)	Treasury Stock
Equity Balance at Dec. 31, 2017		$ 471,662	$ 141	$ 28,203	$ 442,077	$ 1,241	$ 0
Net Income		27,305	0	0	27,305	0	0
Stock issued under Stock Option Plan		1,513	0	931	0	0	582
Common dividends declared,	[1]	(7,908)	0	0	(7,908)	0	0
Other comprehensive gain (loss)		(2,301)	0	0	0	(2,301)	0
Reclassification of Treasury Stock per Maryland Law		0	0	0	582	0	(582)
Equity Balance at Jun. 30, 2018		490,271	141	29,134	461,784	(788)	0
Reclassification of stranded tax effects resulting from change in Federal income tax rate		0	0	0	(272)	272	0
Equity Balance at Mar. 31, 2018		480,000	141	28,624	451,603	(368)	0
Net Income		13,839	0	0	13,839	0	0
Stock issued under Stock Option Plan		809	0	510	0	0	299
Common dividends declared,	[2]	(3,957)	0	0	(3,957)	0	0
Other comprehensive gain (loss)		(420)	0	0	0	(420)	0
Reclassification of Treasury Stock per Maryland Law		0	0	0	299	0	(299)
Equity Balance at Jun. 30, 2018		490,271	141	29,134	461,784	(788)	0
Equity Balance at Dec. 31, 2018		531,977	142	30,121	492,087	9,627	0
Net Income		35,988	0	0	35,988	0	0
Stock issued under Stock Option Plan		2,374	0	1,482	0	0	892
Common dividends declared,	[3]	(19,691)	0	0	(19,691)	0	0
Other comprehensive gain (loss)		22,510	0	0	0	22,510	0
Reclassification of Treasury Stock per Maryland Law		0	0	0	43	0	(43)
Equity Balance at Jun. 30, 2019		572,309	142	31,603	508,427	32,137	0
Purchase of the Company's common stock		(849)	0	0	0	0	(849)
Equity Balance at Mar. 31, 2019		543,635	142	30,916	494,181	18,396	0
Net Income		18,375	0	0	18,375	0	0
Stock issued under Stock Option Plan		1,102	0	687	0	0	415
Common dividends declared,	[4]	(4,544)	0	0	(4,544)	0	0
Other comprehensive gain (loss)		13,741	0	0	0	13,741	0
Reclassification of Treasury Stock per Maryland Law		0	0	0	415	0	(415)
Equity Balance at Jun. 30, 2019		572,309	142	31,603	508,427	32,137	0
Purchase of the Company's common stock		$ 0	$ 0	$ 0	$ 0	$ 0	$ 0

[1] $0.56 per share

[2] $0.28 per share

[3] $1.39 per share

[4] $0.32 per share