Shareholders' Equity (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended	12 Months Ended
	Feb. 20, 2020	May 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Common Shares
Authorized share capital			825,000,000.0
Common shares, shares authorized			800,000,000	800,000,000
Common shares, par value (in dollars per share)			$ 0.001	$ 0.001
Common shares, shares issued			416,198,000	409,652,000
Proceeds from issuance of common shares, net of issuance costs				$ 301,404	$ 8,300
Shares repurchased					3,100,000
Total aggregate amount of shares purchased					$ 18,100
Treasury shares reissued during the year			0	0	0
Dividends to common shareholders (in dollars per share)	$ 0.01		$ 0.04	$ 0.24	$ 0.24
Preferred shares, shares issued			5,613,000	5,750,000
Preferred stock, rate (as a percent)			6.00%	6.00%
Preferred stock, par value (in dollars per share)			$ 0.001	$ 0.001
Preferred stock, liquidation preference (in dollars per share)			50	$ 50
Aggregate net proceeds				$ 277,927
Cash dividend per mandatory convertible preferred shares (in dollars per share)			$ 2.14	$ 2.14
Repurchase of treasury shares					$ 18,071
Preferred shares, shares authorized			25,000,000.0
Mandatory Convertible Preferred Shares
Common Shares
Shares repurchased			136,772
Total aggregate amount of shares purchased			$ 2,900
Preferred shares, shares issued		5,750,000
Preferred stock, rate (as a percent)		6.00%
Preferred stock, par value (in dollars per share)		$ 0.001
Preferred stock, liquidation preference (in dollars per share)		$ 50
Cash dividend per mandatory convertible preferred shares (in dollars per share)	$ 0.75
Mandatory Convertible Preferred Shares | Underwriters option
Common Shares
Preferred shares, shares issued		750,000
Common Stock
Common Shares
Common shares, shares issued				40,250,000
Share price of shares purchased (in dollars per share)				$ 7.75
Proceeds from issuance of common shares, net of issuance costs				$ 301,400
Number of consecutive trading days to calculate average share price of common stock		20 days
Common Stock | Minimum
Common Shares
Conversion ratio		5.3763	5.6751
Common Stock | Maximum
Common Shares
Conversion ratio		6.4516	6.8102
Common Stock | Mandatory Convertible Preferred Shares | Underwriters option
Common Shares
Aggregate net proceeds		$ 277,900