Reinsurance (narrative) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Allowance for reinsurance recoverable
Allowance for uncollectible reinsurance recoverable [Line Items]
Allowance for uncollectible reinsurance recoverable	$ 0	$ 0

Amount of valuation and qualifying accounts and reserves.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SX 210.12-09)
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24092-122690

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