CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (UNAUDITED) - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss, Net of Deferred Taxes [Member]		Unearned Stock Award Common Stock [Member]	Common Stock Held by BMP [Member]	Treasury Stock, at Cost [Member]	Total
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Reclassification of unrealized gains and losses on marketable equity securities | ASU 2016-01 [Member]	$ 0	$ 0	$ 153	$ (153)	[1]	$ 0	$ 0	$ 0	$ 0
Balance at Dec. 31, 2017	536	276,730	535,130	(3,641)		(2,894)	(2,736)	(204,558)	598,567
Balance (ASU 2016-01 [Member]) at Dec. 31, 2017	$ 536	276,730	535,283	(3,794)		(2,894)	(2,736)	(204,558)	598,567
Balance (in shares) at Dec. 31, 2017	37,419,070
Balance (in shares) (ASU 2016-01 [Member]) at Dec. 31, 2017	37,419,070
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	$ 0	0	14,745	0		0	0	0	14,745
Other comprehensive income (loss), net of tax	0	0	0	(275)		0	0	0	(275)
Exercise of stock options, net	$ 1	454	0	0		0	0	(165)	290
Exercise of stock options, net (in shares)	19,726
Release of shares, net of forfeitures	$ 0	426	0	0		(1,349)	0	923	0
Release of shares, net of forfeitures (in shares)	73,019
Stock-based compensation	$ 0	0	0	0		388	0	0	388
Shares received to satisfy distribution of retirement benefits	$ 0	(540)	0	0		0	540	(524)	(524)
Shares received to satisfy distribution of retirement benefits (in shares)	(27,545)
Reclassification of tax effects on other comprehensive income (loss)	$ 0	0	(32)	32		0	0	0	0
Cash dividends declared and paid	0	0	(5,234)	0		0	0	0	(5,234)
Balance at Mar. 31, 2018	$ 537	277,070	544,762	(4,037)		(3,855)	(2,196)	(204,324)	607,957
Balance (in shares) at Mar. 31, 2018	37,484,270
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Reclassification of unrealized gains and losses on marketable equity securities | ASU 2016-01 [Member]			153	(153)
Balance at Dec. 31, 2018	$ 537	277,512	565,713	(6,500)		(3,623)	(1,509)	(230,049)	$ 602,081
Balance (in shares) at Dec. 31, 2018	36,081,455								36,081,455
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	$ 0	0	11,501	0		0	0	0	$ 11,501
Other comprehensive income (loss), net of tax	0	0	0	1,268		0	0	0	1,268
Release of shares, net of forfeitures	$ 0	846	0	0		(2,729)	0	1,883	0
Release of shares, net of forfeitures (in shares)	138,329
Stock-based compensation	$ 0	0	0	0		284	0	0	284
Payments related to tax withholding for stock-based compensation	$ 0	0	0	0		0	0	(7)	(7)
Payments related to tax withholding for stock-based compensation (in shares)	(418)
Cash dividends declared and paid	$ 0	0	(5,039)	0		0	0	0	(5,039)
Repurchase of shares of Common Stock	0	0	0	0		0	0	$ (3,814)	(3,814)
Repurchase of shares of Common Stock (in shares)								(199,254)
Balance at Mar. 31, 2019	$ 537	$ 278,358	$ 572,175	$ (5,232)		$ (6,068)	$ (1,509)	$ (231,987)	$ 606,274
Balance (in shares) at Mar. 31, 2019	36,020,112								36,020,112

[1] Represents the impact of adopting ASU 2016-01 allowing the reclassification of unrealized gains and losses on available-for-sale equity securities from accumulated other comprehensive income to retained earnings.