Derivative Instruments and Hedging Activities - Interest Rate Swaps and Interest Rate Caps (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash Flow Hedging \| Designated as Hedging Instrument \| Interest Rate Swap
Derivative [Line Items]
Interest expense-investment securities	$ 1,619	$ 1,848	$ 1,737

Interest expense on all other items not previously classified. For example, includes dividends associated with redeemable preferred stock of a subsidiary that is treated as a liability in the parent's consolidated balance sheet.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4D
-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5624177-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph -4
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

Name:	us-gaap_InterestExpenseOther
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration