Organization and Basis of Presentation - Allowance For Credit Loss (Details) - USD ($) $ in Thousands	6 Months Ended
Jun. 30, 2020	Jan. 01, 2020
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance	$ 0
Impact of adoption ASC 326	13,644
Provision for credit losses	97
Ending balance	13,644
Mortgage Backed Securities
Financing Receivable, Allowance for Credit Loss [Line Items]
Beginning balance	0
Impact of adoption ASC 326	13,644
Provision for credit losses	0
Ending balance	$ 13,644
Cumulative Effect, Period Of Adoption, Adjustment \| Mortgage Backed Securities
Financing Receivable, Allowance for Credit Loss [Line Items]
Impact of adoption ASC 326		$ 13,644

Amount of expense related loan transactions, lease transactions, credit loss from transactions other than loan and lease transactions, and other loss based on assessment of uncollectability from the counterparty to reduce the account to their net realizable value.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953423-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.11)
-URI http://asc.fasb.org/extlink&oid=120399700&loc=SL114874048-224260

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585

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