Fair Value Measures (Reconciliation of Changes in Assets and Liabilities with Unobservable Inputs) (Details) - CMBS [Member] - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 53,304	$ 58,646
Total gains and losses:
Unrealized loss included in other comprehensive income, net	(1,599)	(232)
Purchases, issuances, settlements and amortization:
Principal payments received	(3,786)	(4,055)
Amortization included in net income	179	96
Ending balance	$ 48,098	$ 54,455