Commercial Mortgage Banking - Summary of Changes in Carrying Value of Mortgage Servicing Rights (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013
Transfers and Servicing [Abstract]
Balance at beginning of period	$ 28,879		$ 26,983
Originations	2,474	[1]	4,638	[1]
Purchases	52		1,165
Disposals	(776)	[1]	(4,583)	[1]
Amortization expense	(1,514)		(538)
Balance at end of period	$ 29,115		$ 27,665

[1] Includes refinancings