Commercial Mortgage Banking - Summary of Changes in Carrying Value of Mortgage Servicing Rights (Details) - USD ($) $ in Thousands		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014
Transfers and Servicing [Abstract]
Balance at beginning of period		$ 30,140	$ 28,879
Originations	[1]	3,491	2,474
Purchases		653	52
Disposals	[1]	(4,569)	(776)
Amortization expense		(495)	(1,514)
Balance at end of period		$ 29,220	$ 29,115

[1] Includes refinancings