Share Transactions - Issuance of preferred shares (Details) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions	1 Months Ended	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2021	Jun. 30, 2020
Class of Stock [Line Items]
Proceeds from issuance of preferred shares, net		$ 485,821	$ 0
Series G Preferred Shares
Class of Stock [Line Items]
Preferred shares issued	$ 500,000
Preferred shares, dividend rate (as a percent)	4.55%
Preferred shares, par value per share	$ 0.01	$ 0.01
Liquidation preference per share	25,000	25,000
Preferred shares, redemption price per share	$ 25,000	$ 25,000
Proceeds from issuance of preferred shares, net	$ 485,800
Series G Depositary Share Equivalent
Class of Stock [Line Items]
Preference shares, number of shares issued	20.0
Proportionate interest of preference shares, per depositary share	0.10%	0.10%
Liquidation preference per share	$ 25	$ 25
Preferred shares, redemption price per share	$ 25	$ 25