Summary of Significant Accounting Policies Additional Details (Details)	3 Months Ended	6 Months Ended
	Jun. 30, 2020 USD ($)	Jun. 30, 2020 USD ($) segment	Jun. 30, 2019 USD ($)	Jan. 01, 2020 USD ($)
Accounting Policies [Abstract]
Number of operating segments | segment		1
Statement of cash flows reclassification from operating activities to investing activities			$ 254,000,000
Allowance for credit losses	$ 55,000,000	$ 55,000,000		$ 47,000,000
Write-offs charged against allowance	$ 0	$ 0