Financing Receivables Financing Receivables (Troubled Debt Restructurings) (Details) loan in Millions, $ in Millions	3 Months Ended
Mar. 31, 2021 USD ($) loan	Mar. 31, 2020 loan
Receivables [Abstract]
Loans accounted for as troubled debt restructuring \| loan	0	0
Commitments to lend additional funds to borrowers whose loans have been restructured \| $	$ 0

Amount of unfunded portion of contractual agreement to lend funds to borrower for financing receivable modified as troubled debt restructuring.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=121585226&loc=d3e18794-111554

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