Earnings Per Common Share and Stockholders' Equity (Stockholders' Equity) (Details) - USD ($) $ / shares in Units, $ in Thousands						3 Months Ended	9 Months Ended
	Sep. 01, 2020	Jun. 10, 2020	Jun. 01, 2020	Mar. 01, 2020	Nov. 21, 2019	Sep. 30, 2020	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Class of Stock [Line Items]
Proceeds from issuance of preferred stock, net							$ 290,260	$ 0
Dividends paid on preferred stock						$ 5,950	$ 18,511
Preferred Stock, Series B
Class of Stock [Line Items]
Preferred stock, shares issued		12,000				12,000	12,000		0
Preferred stock, dividend rate, percentage		6.625%
Preferred stock, par value per share		$ 1.00				$ 1	$ 1
Preferred stock, liquidation preference, per share		$ 25,000
Proceeds from issuance of preferred stock, net		$ 290,300
Preferred Stock, Series A
Class of Stock [Line Items]
Preferred stock, shares issued					16,000	16,000	16,000		16,000
Preferred stock, dividend rate, percentage					5.95%
Preferred stock, par value per share					$ 1.00	$ 1	$ 1		$ 1
Preferred stock, liquidation preference, per share					$ 25,000
Proceeds from issuance of preferred stock, net					$ 388,900
Dividends paid on preferred stock	$ 5,900		$ 6,000	$ 6,600