Leases - Lease Related Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Assets
Operating lease assets	$ 29
Finance lease assets	37	$ 41
Total lease assets	66
Liabilities
Operating lease liabilities, current	5	0
Finance lease liabilities, current	5
Operating lease liabilities, noncurrent	24
Finance lease liabilities, noncurrent	55	$ 59
Total lease liabilities	$ 89