Commitments and Contingencies - Mortgage Loan Loss Reserve Activity (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Commitment And Contingencies [Abstract]
Balance at beginning of period	$ 969	$ 639	$ 805	$ 442
Expense provisions	324	161	574	455
Cash payments	(70)	(1)	(156)	(98)
Balance at end of period	$ 1,223	$ 799	$ 1,223	$ 799