Summary of Significant Accounting Policies - Earnings (Loss) per Share (Details) - shares	3 Months Ended				12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted average shares outstanding - basic and diluted (in shares)	179,288,782	171,378,608	171,278,819	171,231,111	181,506,875	173,313,575	171,850,041
Convertible Debt Securities
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded (in shares)					18,100,000	0	0
Options, SARs and RSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded (in shares)					15,200,000	13,100,000	8,900,000
PSUs
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Securities excluded (in shares)					2,000,000.0	2,100,000	1,200,000