Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Billions	Dec. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Common stock, par value in dollars per share	$ 0.01	$ 0.01
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	135,003,662	123,435,738
Common stock, shares outstanding	135,003,662	123,435,738
Variable interest entity, consolidated, carrying amount, assets	$ 1.4	$ 1.5
Variable interest entity, consolidated, carrying amount, liabilities	$ 1.2	$ 1.3