Summary of Significant Accounting Policies - Additional Information (Details) - USD ($) $ in Millions	Sep. 30, 2020	Jan. 01, 2020	Dec. 31, 2019
Significant Accounting Policies [Line Items]
Retained earnings	$ (2,233)		$ (2,282)
ASU 2016-13
Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adoption date	Jan. 01, 2020
Change in accounting principle, accounting standards update, early adoption	false
Change in accounting principle, accounting standards update, adopted	true
ASU 2016-13 | Cumulative-Effect Adjustment
Significant Accounting Policies [Line Items]
Retained earnings		$ 5
ASU 2018-13
Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adoption date	Jan. 01, 2020
Change in accounting principle, accounting standards update, early adoption	false
Change in accounting principle, accounting standards update, adopted	true
Change in accounting principle, accounting standards update, immaterial effect	true