Consolidated Statements of Stockholders' Equity - 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, 2015		$ 398,227	$ 139	$ 24,371	$ 368,053	$ 5,664	$ 0
Stock issued under Stock Option Plan		2,593	0	1,571	0	0	1,022
Common dividends declared	[1]	(12,250)	0	0	(12,250)	0	0
Other comprehensive gain (loss)		(4,106)	0	0	0	(4,106)	0
Reclassification of Treasury Stock per Maryland Law		0	1	0	1,021	0	(1,022)
Common dividends declared	[1]	(12,250)	0	0	(12,250)	0	0
Net income		45,342	0	0	45,342	0	0
Common dividends declared	[1]	(12,250)	0	0	(12,250)	0	0
Equity Balance at Dec. 31, 2016		429,806	140	25,942	402,166	1,558	0
Stock issued under Stock Option Plan		3,811	0	2,261	0	0	1,550
Common dividends declared	[2]	(13,202)	0	0	(13,202)	0	0
Other comprehensive gain (loss)		(317)	0	0	0	(317)	0
Reclassification of Treasury Stock per Maryland Law		0	1	0	1,549	0	(1,550)
Common dividends declared	[2]	(13,202)	0	0	(13,202)	0	0
Net income		51,564	0	0	51,564	0	0
Common dividends declared	[2]	(13,202)	0	0	(13,202)	0	0
Equity Balance at Dec. 31, 2017		471,662	141	28,203	442,077	1,241	0
Stock issued under Stock Option Plan		2,961	0	1,918	0	0	1,043
Common dividends declared	[3]	(16,966)	0	0	(16,966)	0	0
Other comprehensive gain (loss)		8,114	0	0	0	8,114	0
Reclassification of Treasury Stock per Maryland Law		0	1	0	139	0	(140)
Common dividends declared	[3]	(16,966)	0	0	(16,966)	0	0
Net income		67,109	0	0	67,109	0	0
Common dividends declared	[3]	(16,966)	0	0	(16,966)	0	0
Purchase of the Company's common stock		(903)	0	0	0	0	(903)
Reclassification of stranded tax effects resulting from change in Federal income tax rate		0	0	0	(272)	272	0
Equity Balance at Dec. 31, 2018		$ 531,977	$ 142	$ 30,121	$ 492,087	$ 9,627	$ 0

[1] $.88 per share dividend.

[2] $.94 per share dividend.

[3] $1.20 per share dividend.