Leases - Summary of Cash Flows Related to Leases (Details) - USD ($)	3 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2019
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from finance leases		$ 1,000,000
Operating cash flows from operating leases		146,000,000
Financing cash flows from finance leases		2,000,000
Right-of-use assets obtained in exchange for lease obligations: (b)
Operating leases		81,000,000
Net gain recognized from sale leaseback transaction		14,000,000
Finance leases		$ 0
Proceeds from sale leaseback transaction	$ 16,000,000