CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss, Net of Deferred Taxes [Member]	Unallocated Common Stock of ESOP [Member]	Unearned Restricted Stock Award Common Stock [Member]	Common Stock Held by BMP [Member]	Treasury Stock [Member]	Total
Balance at Dec. 31, 2012	$ 520	$ 239,041	$ 379,166	$ (9,640)	$ (3,007)	$ (3,122)	$ (8,800)	$ (202,584)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income recognized during the period, net of tax				4,881					$ 4,881
Shares issued in exercise of options (455,310 shares, 16,960 shares and 833,334 shares during the years ended December 31, 2015, 2014, and 2013, respectively)	8	11,220
Excess Tax benefit of stock benefit plans		292
Amortization of excess fair value over cost - ESOP stock and stock options expense		1,176
Treasury shares repurchased (20,000 shares during the year ended December 31, 2015)								0	0
Release from treasury stock for equity plans, net of return of shares to treasury for forfeited shares (81,663 shares, 125,108 shares and 165,348 shares during the years ended December 31, 2015, 2014, and 2013, respectively)		524				(2,082)	(213)	2,064
Net income for the period			43,548						43,548
Cash dividends declared and paid			(19,728)
Amortization of earned portion of ESOP stock					231
Amortization of earned portion of restricted stock awards						2,011
Balance at Dec. 31, 2013	528	252,253	402,986	(4,759)	(2,776)	(3,193)	(9,013)	(200,520)	435,506
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income recognized during the period, net of tax				(3,788)					(3,788)
Shares issued in exercise of options (455,310 shares, 16,960 shares and 833,334 shares during the years ended December 31, 2015, 2014, and 2013, respectively)	1	277
Excess Tax benefit of stock benefit plans		71
Amortization of excess fair value over cost - ESOP stock and stock options expense		1,111
Treasury shares repurchased (20,000 shares during the year ended December 31, 2015)								0	0
Release from treasury stock for equity plans, net of return of shares to treasury for forfeited shares (81,663 shares, 125,108 shares and 165,348 shares during the years ended December 31, 2015, 2014, and 2013, respectively)		646				(1,849)	(151)	1,554
Net income for the period			44,246						44,246
Cash dividends declared and paid			(20,106)
Amortization of earned portion of ESOP stock					231
Amortization of earned portion of restricted stock awards						1,976
Balance at Dec. 31, 2014	529	254,358	427,126	(8,547)	(2,545)	(3,066)	(9,164)	(198,966)	459,725
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income recognized during the period, net of tax				(254)					(254)
Shares issued in exercise of options (455,310 shares, 16,960 shares and 833,334 shares during the years ended December 31, 2015, 2014, and 2013, respectively)	4	6,545
Excess Tax benefit of stock benefit plans		303
Amortization of excess fair value over cost - ESOP stock and stock options expense		1,105
Treasury shares repurchased (20,000 shares during the year ended December 31, 2015)								(300)	(300)
Release from treasury stock for equity plans, net of return of shares to treasury for forfeited shares (81,663 shares, 125,108 shares and 165,348 shares during the years ended December 31, 2015, 2014, and 2013, respectively)		487				(1,061)	(190)	1,015
Net income for the period			44,772						44,772
Cash dividends declared and paid			(20,292)
Amortization of earned portion of ESOP stock					232
Amortization of earned portion of restricted stock awards						1,856
Balance at Dec. 31, 2015	$ 533	$ 262,798	$ 451,606	$ (8,801)	$ (2,313)	$ (2,271)	$ (9,354)	$ (198,251)	$ 493,947