Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Millions		Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2018
Statement of Cash Flows [Abstract]
Cash and cash equivalents		$ 33	$ 106	$ 79	$ 54
Restricted cash included in Other long-term assets		11	14	11	11
Total cash, cash equivalents and restricted cash at end of period	[1]	$ 44	$ 120	$ 90	$ 65

[1] The following table reconciles cash, cash equivalents and restricted cash per the statement of cash flows to the balance sheet. The restricted cash balances are primarily due to letters of credit which have been issued to the landlords of leased office space. The terms of the letters of credit primarily extend beyond one year. (in millions)September 30, 2020December 31, 2019September 30, 2019December 31, 2018Cash and cash equivalents$33 $106 $79 $54 Restricted cash included in Other long-term assets11 14 11 11 Total cash, cash equivalents and restricted cash at end of period$44 $120 $90 $65