Summary of Significant Accounting Policies - 10-K - Recent Adopted Accounting Policies (Details) - USD ($) $ in Millions	Dec. 31, 2019	Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets	$ 466	$ 347
Lease liabilities	$ 502
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets		347
Lease liabilities		$ 369