Loans and Other Repossessed Assets Acquired (Detail) - Schedule of Consumer Credit Quality (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012		Dec. 31, 2011		Sep. 30, 2011
Performing Financing Receivable [Member] | Home Equity Loans [Member]
Commercial Credit Quality	$ 355,983	[1]	$ 347,355	[1]	$ 361,420	[1]
Performing Financing Receivable [Member] | Manufactured Housing [Member]
Commercial Credit Quality	276,522	[1]	271,814	[1]	273,125	[1]
Performing Financing Receivable [Member] | Marine [Member]
Commercial Credit Quality	75,544	[1]	52,344	[1]	55,196	[1]
Performing Financing Receivable [Member] | Other Consumer [Member]
Commercial Credit Quality	41,644	[1]	49,748	[1]	52,791	[1]
Performing Financing Receivable [Member] | Consumer Loan [Member]
Commercial Credit Quality	749,693	[1]	721,261	[1]	742,532	[1]
Performing Classified [Member] | Home Equity Loans [Member]
Commercial Credit Quality	6,858	[1]	1,254	[1]	407	[1]
Performing Classified [Member] | Manufactured Housing [Member]
Commercial Credit Quality	87	[1]		[1]		[1]
Performing Classified [Member] | Marine [Member]
Commercial Credit Quality	53	[1]		[1]		[1]
Performing Classified [Member] | Other Consumer [Member]
Commercial Credit Quality	59	[1]	121	[1]		[1]
Performing Classified [Member] | Consumer Loan [Member]
Commercial Credit Quality	7,057	[1]	1,375	[1]	407	[1]
Nonperforming Financing Receivable [Member] | Home Equity Loans [Member]
Commercial Credit Quality	10,551	[1]	8,192	[1]	6,871	[1]
Nonperforming Financing Receivable [Member] | Manufactured Housing [Member]
Commercial Credit Quality	3,491	[1]	3,461	[1]	2,922	[1]
Nonperforming Financing Receivable [Member] | Marine [Member]
Commercial Credit Quality	139	[1]	246	[1]	47	[1]
Nonperforming Financing Receivable [Member] | Other Consumer [Member]
Commercial Credit Quality	318	[1]	224	[1]	298	[1]
Nonperforming Financing Receivable [Member] | Consumer Loan [Member]
Commercial Credit Quality	14,499	[1]	12,123	[1]	10,138	[1]
Total consumer loans [Member] | Home Equity Loans [Member]
Commercial Credit Quality	373,392	[1]	356,801	[1]	368,698	[1]
Total consumer loans [Member] | Manufactured Housing [Member]
Commercial Credit Quality	280,100	[1]	275,275	[1]	276,047	[1]
Total consumer loans [Member] | Marine [Member]
Commercial Credit Quality	75,736		52,590	[1]	55,243	[1]
Total consumer loans [Member] | Other Consumer [Member]
Commercial Credit Quality	42,021	[1]	50,093	[1]	53,089	[1]
Total consumer loans [Member] | Consumer Loan [Member]
Commercial Credit Quality	771,249	[1]	734,759	[1]	753,077	[1]
ASC-310-30 loans [Member] | Home Equity Loans [Member]
Commercial Credit Quality	11,272	[1]	469	[1]	515	[1]
ASC-310-30 loans [Member] | Manufactured Housing [Member]
Commercial Credit Quality		[1]		[1]		[1]
ASC-310-30 loans [Member] | Marine [Member]
Commercial Credit Quality		[1]		[1]		[1]
ASC-310-30 loans [Member] | Other Consumer [Member]
Commercial Credit Quality	151	[1]	25	[1]	29	[1]
ASC-310-30 loans [Member] | Consumer Loan [Member]
Commercial Credit Quality	11,423	[1]	494	[1]	544	[1]
Home Equity Loans [Member]
Commercial Credit Quality	384,664	[1]	357,270	[1]	369,213	[1]
Manufactured Housing [Member]
Commercial Credit Quality	280,100	[1]	275,275	[1]	276,047	[1]
Marine [Member]
Commercial Credit Quality	75,736	[1]	52,590	[1]	55,243	[1]
Other Consumer [Member]
Commercial Credit Quality	42,172	[1]	50,118	[1]	53,118	[1]
Consumer Loan [Member]
Commercial Credit Quality	$ 782,672	[1]	$ 735,253	[1]	$ 753,621	[1]

[1] Credit quality indicators are reviewed and updated as applicable on an ongoing basis in accordance with credit policies.