Securities - Additional Information (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Schedule Of Available For Sale Securities [Line Items]
Loans pledged as collateral	$ 3,900.0
Weighted average yield, total	5.27%	5.25%
US Treasury Securities \| Other
Schedule Of Available For Sale Securities [Line Items]
Loans pledged as collateral	$ 0.4
Agency Mortgage-backed Securities
Schedule Of Available For Sale Securities [Line Items]
Loans pledged as collateral	$ 148.0
Agency Mortgage-backed Securities and Beneficial interests in FHLMC securitization
Schedule Of Available For Sale Securities [Line Items]
Weighted average yield, total	2.66%	2.91%

Carrying amount as of the balance sheet date of loans that have been pledged as collateral for borrowings. If the secured party has the right by contract or custom to sell or re-pledge the collateral, then the debtor reclassifies that asset and report that asset in its statement of financial position separately from other assets not so encumbered.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=66007379&loc=d3e113888-111728

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5086-111524

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