Fair Value Measurements - Narrative (Details) $ in Millions	1 Months Ended
Jun. 30, 2019 USD ($)
Fair Value Disclosures [Abstract]
Investments sold	$ 41

The cash inflow associated with the sale of investments that are pledged or subject to withdrawal restrictions during the period.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3179-108585

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