Related Party Transactions (Schedule of Dividends Paid to Manager) (Details) - USD ($) $ / shares in Units, $ in Millions	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Related Party Transactions [Abstract]
Cash dividend declared per share (in dollars per share)	$ 1.00	$ 1.00	$ 1.00	$ 1.00	$ 1.00
Cash Paid to Manager	$ 13	$ 13	$ 13	$ 13	$ 13

The per share amount of a dividend declared, but not paid, as of the financial reporting date.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4304-108586

Name:	us-gaap_DividendsPayableAmountPerShare
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant