CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Common stock, shares authorized (in shares)	500,000,000	500,000,000
Common stock, par value per share (in dollars per share)	$ 0.001	$ 0.001
Common shares, issued (in shares)	86,600,302	85,800,303
Common stock, shares, outstanding (in shares)	86,600,302	85,800,303
Preferred stock, authorized (in shares)	100,000,000	100,000,000
Preferred stock, par value per share (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares outstanding (in shares)	0	0
Preferred stock, issued (in shares)	0	0
Special stock shares issued (in shares)	100	100
Special stock par value per share (in shares)	$ 0.001	$ 0.001
Special stock shares outstanding (in shares)	100	100
Noncontrolling interests		$ 141