Condensed Statements of Income (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 30, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 30, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
INCOME
Interest Income									$ 50	$ 38	$ 30
Net Gain on Securities									1,667	3,024	0
Other Income									70	71	76
TOTAL INTEREST INCOME	18,917	18,953	19,563	19,727	20,016	20,105	20,521	19,519	77,160	80,161	64,193
EXPENSE
Salaries and Employee Benefits									29,086	27,992	22,070
Professional Fees									2,247	2,056	2,285
Occupancy and Equipment Expense									7	8	8
Interest Expense									10,912	16,180	15,522
Other Expenses									359	357	281
INCOME BEFORE INCOME TAXES AND EQUITY IN UNDISTRIBUTED INCOME OF SUBSIDIARIES									34,724	27,975	19,028
Income Tax Benefit									10,669	7,726	5,623
INCOME BEFORE EQUITY IN UNDISTRIBUTED INCOME OF SUBSIDIARIES									15,561	22,831	11,855
Equity in Undistributed (Excess Distributed) Income of Subsidiaries									8,494	(2,582)	1,550
NET INCOME	6,194	6,292	5,967	5,602	5,573	5,167	4,864	4,645	24,055	20,249	13,405
Other Comprehensive Income (Loss):
Changes in Unrealized Gain (Loss) on Securities, Available-for-Sale									(124)	5,677	474
Change in Unrecognized Amounts in Pension, Net									(47)	4	(13)
Changes in Unrecognized Loss on Postretirement Benefit Obligation, Net									(21)	(38)	(176)
TOTAL COMPREHENSIVE INCOME									23,863	25,892	13,690
Parent Company [Member]
INCOME
Interest Income									50	38	30
Net Gain on Securities									0	935	0
Other Income									70	71	76
TOTAL INTEREST INCOME									17,620	24,894	14,106
EXPENSE
Salaries and Employee Benefits									458	444	420
Professional Fees									352	379	842
Occupancy and Equipment Expense									7	8	8
Interest Expense									2,221	2,239	1,878
Other Expenses									359	357	281
Total Expenses									3,397	3,427	3,429
INCOME BEFORE INCOME TAXES AND EQUITY IN UNDISTRIBUTED INCOME OF SUBSIDIARIES									14,223	21,467	10,677
Income Tax Benefit									1,338	1,364	1,178
INCOME BEFORE EQUITY IN UNDISTRIBUTED INCOME OF SUBSIDIARIES									15,561	22,831	11,855
Equity in Undistributed (Excess Distributed) Income of Subsidiaries									8,494	(2,582)	1,550
NET INCOME									24,055	20,249	13,405
Other Comprehensive Income (Loss):
Changes in Unrealized Gain (Loss) on Securities, Available-for-Sale									(124)	5,677	474
Change in Unrecognized Amounts in Pension, Net									47	(4)	13
Changes in Unrecognized Loss on Postretirement Benefit Obligation, Net									(21)	(38)	(176)
TOTAL COMPREHENSIVE INCOME									23,863	25,892	13,690
Bank [Member]
INCOME
Dividends from Subsidiaries									17,500	22,500	14,000
Non Bank [Member]
INCOME
Dividends from Subsidiaries									$ 0	$ 1,350	$ 0