Derivatives - Notional and Fair Value Amounts of Derivative Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Derivative [Line Items]
Notional amount	$ 287,100	$ 318,000
Fair value	16,805	13,239
Bank of America, N.A.
Derivative [Line Items]
Notional amount	205,200	174,900
Fair value	14,006	8,523
Barclays Bank PLC
Derivative [Line Items]
Notional amount	81,900	115,300
Fair value	2,799	3,347
Citigroup Inc.
Derivative [Line Items]
Notional amount	0	0
Fair value	0	0
Credit Suisse International
Derivative [Line Items]
Notional amount	0	0
Fair value	0	0
Societe Generale
Derivative [Line Items]
Notional amount	0	27,800
Fair value	$ 0	$ 1,369

Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226008-175313

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=121572278&loc=d3e13433-108611

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

Name:	us-gaap_DerivativeAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant