Preferred Stock (Details) $ / shares in Units, $ in Thousands	1 Months Ended		12 Months Ended
	Oct. 31, 2019 USD ($) $ / shares shares	Oct. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2020 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) shares	Dec. 31, 2018 USD ($)
Class of Stock [Line Items]
Stock issuance costs | $			$ 2,212	$ 17,521	$ 3,947
Ratio of depositary share to underlying preferred stock		0.01
Redemption price per share (in dollars per share) | $ / shares			$ 2,500.00
Stated liquidation value per share (in dollars per share) | $ / shares			$ 25.00
Preferred stock, shares redeemed (in shares) | shares				11,500,000
Excess of redemption value over carrying value of preferred shares redeemed | $			$ 0	$ 9,856	$ 0
Series F Preferred Stock
Class of Stock [Line Items]
Dividend rate		5.20%	5.20%	5.20%
Depositary shares outstanding (in shares) | shares		13,800,000	138,000	138,000
Gross proceeds | $		$ 345,000
Stock issuance costs | $		$ 10,897
Dividend per depositary share (in dollars per share) | $ / shares		$ 1.300000
Underwriters over allotment of shares (in shares) | shares		1,800,000
Series E Preferred Stock
Class of Stock [Line Items]
Dividend rate	5.70%
Stated liquidation value per share (in dollars per share) | $ / shares	$ 25.00
Preferred stock, shares redeemed (in shares) | shares	11,500,000
Aggregate redemption price (in dollars per share) | $ / shares	$ 25.079167
Excess of redemption value over carrying value of preferred shares redeemed | $	$ 9,856