Investments Gross Unrealized Losses and Fair Value, Aggregated by Investment Category and Length of Time, in Continuous Unrealized Loss Position (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Total, Fair Value	$ 13,309	$ 28,458
Collateralized mortgage obligations, Government sponsored agencies
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	4,962
Less than 12 months, Unrealized Losses	(10)
Total, Fair Value	4,962
Total, Unrealized Losses	(10)
Federal agencies
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	4,998
Less than 12 months, Unrealized Losses	(2)
Total, Fair Value	4,998
Total, Unrealized Losses	(2)
Municipals
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	874	971
Less than 12 months, Unrealized Losses	(16)	(14)
Total, Fair Value	874	971
Total, Unrealized Losses	(16)	(14)
Corporate obligations
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value		19,957
Less than 12 months, Unrealized Losses		(790)
12 months or more, Fair Value	2,475	2,454
12 months or more, Unrealized Losses	(4,269)	(4,299)
Total, Fair Value	2,475	22,411
Total, Unrealized Losses	(4,269)	(5,089)
Total temporarily impaired securities
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value	10,834	26,004
Less than 12 months, Unrealized Losses	(28)	(810)
12 months or more, Fair Value	2,475	2,454
12 months or more, Unrealized Losses	(4,269)	(4,299)
Total, Fair Value	13,309	28,458
Total, Unrealized Losses	(4,297)	(5,109)
Mortgage-backed securities, Government sponsored agencies
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, Fair Value		5,076
Less than 12 months, Unrealized Losses		(6)
Total, Fair Value		5,076
Total, Unrealized Losses		$ (6)