Commercial Mortgage Banking - Summary of Changes in Carrying Value of Mortgage Servicing Rights (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014
Servicing Asset at Amortized Cost, Balance [Roll Forward]
Balance at beginning of year		$ 30,140	$ 28,879
Originations	[1]	6,569	5,956
Purchases		799	345
Disposals	[1]	(8,613)	(2,221)
Amortization expense		(727)	(2,819)
Balance at end of year		$ 28,168	$ 30,140

[1] Includes refinancings