Related Party Transactions - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended				6 Months Ended	12 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012	Dec. 31, 2011	Jun. 30, 2013 Demand Deposits	Dec. 31, 2012 Demand Deposits	Jun. 30, 2013 Trust Preferred Securities	Jun. 30, 2013 Maximum
Related Party Transaction [Line Items]
Percentage of ownership held by President of Parent Company and Director										1.00%
Cash and cash equivalents	$ 60,401	$ 44,265	$ 60,401	$ 44,265	$ 100,041	$ 29,720	$ 763	$ 239
Restricted cash	99,119		99,119		90,641		433	289
Interest income							0	0
Lease rent paid	74	53	164	132
Sublease rent received	43	44	87	87
Fees received for managing securitization of marketable securities	$ 603,173		$ 603,173		$ 655,509				$ 25,000