Derivative Instruments - Schedule of settlement of fair value hedges (Details) - Fair value hedging - Deposit liabilities - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Derivative [Line Items]
Cumulative reduction to interest expense	$ 115,323	$ 106,056
Remaining balance	$ 117,872		$ 127,139
Weighted average years remaining to maturity	20 years 1 month 6 days	21 years 2 months 12 days

Fair value of all derivative liabilities designated as fair value hedging instruments.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5624163-113959

Name:	us-gaap_FairValueHedgeLiabilitiesAtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant