Shareholders’ Equity (Details) $ / shares in Units, $ in Thousands								1 Months Ended		3 Months Ended		6 Months Ended		12 Months Ended
	Nov. 01, 2018 USD ($)	Aug. 01, 2018 USD ($)	Jul. 27, 2018 $ / shares	Jul. 03, 2018 USD ($)	Jun. 06, 2018 $ / shares	May 08, 2018 USD ($)	Apr. 20, 2018 $ / shares	Jun. 30, 2018 USD ($) $ / shares shares	May 31, 2018 $ / shares shares	Jun. 30, 2018 $ / shares shares	Jun. 30, 2017 $ / shares	Jun. 30, 2018 USD ($) $ / shares shares	Jun. 30, 2017 USD ($) $ / shares	Dec. 31, 2017 USD ($) shares
Common Shares
Common shares, shares issued | shares								410,252,000		410,252,000		410,252,000		367,510,000
Proceeds from issuance of common shares, net of issuance costs | $								$ 21,800				$ 302,014	$ 8,300
Shares repurchased | shares														3,100,000
Total aggregate amount of shares purchased | $														$ 18,100
Common stock dividend declared (in dollars per share) | $ / shares			$ 0.06				$ 0.06			$ 0.06	$ 0.06	$ 0.12	$ 0.12
Cash dividends paid | $				$ 21,500								$ 36,200	$ 34,197
Preferred shares, shares issued | shares								5,750,000		5,750,000		5,750,000
Preferred stock, rate (as a percent)												6.00%
Preferred stock, par value (in dollars per share) | $ / shares								$ 0.001		$ 0.001		$ 0.001
Preferred stock, liquidation preference (in dollars per share) | $ / shares								$ 50		$ 50		$ 50
Aggregate net proceeds | $												$ 278,573
Mandatory Convertible Preferred Shares
Common Shares
Cash dividends paid | $	$ 4,300	$ 3,700
Preferred shares, shares issued | shares									5,750,000,000
Preferred stock, rate (as a percent)									6.00%
Preferred stock, par value (in dollars per share) | $ / shares									$ 0.001
Preferred stock, liquidation preference (in dollars per share) | $ / shares									$ 50
Cash dividend per mandatory convertible preferred shares | $ / shares			$ 0.75		$ 0.64							$ 0.64
Mandatory Convertible Preferred Shares | Underwriters option
Common Shares
Preferred shares, shares issued | shares									750,000
Common Shares
Common Shares
Common shares, shares issued | shares									35,000,000,000
Share price of shares purchased (in dollars per share) | $ / shares									$ 7.75
Proceeds from issuance of common shares, net of issuance costs | $								$ 302,000
Number of consecutive trading days to calculate average share price of common stock									20 days
Common Shares | Underwriters option
Common Shares
Common shares, shares issued | shares								5,250,000,000		5,250,000,000		5,250,000,000
Common Shares | Minimum
Common Shares
Conversion ratio									5.3763
Common Shares | Maximum
Common Shares
Conversion ratio									6.4516
Common Shares | Mandatory Convertible Preferred Shares | Underwriters option
Common Shares
Aggregate net proceeds | $						$ 278,600