CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) - USD ($) $ in Millions		Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Statement of Cash Flows [Abstract]
Cash and cash equivalents		$ 59	$ 71	$ 40	$ 106
Restricted cash included in Other long-term assets		8	12	12	14
Total cash, cash equivalents and restricted cash at end of period	[1]	$ 67	$ 83	$ 52	$ 120

[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)March 31, 2021December 31, 2020March 31, 2020December 31, 2019Cash and cash equivalents$59 $71 $40 $106 Restricted cash included in Other long-term assets8 12 12 14 Total cash, cash equivalents and restricted cash at end of period$67 $83 $52 $120