Stockholders' Equity (Stock Transactions - Narrative) (Details) - USD ($)			1 Months Ended	3 Months Ended				9 Months Ended		10 Months Ended
	Oct. 29, 2019	Mar. 19, 2019	Oct. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Oct. 31, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Common stock, par value (dollars per share)				$ 0.01				$ 0.01			$ 0.01
Proceeds from issuance of common stock								$ 192,514,000	$ 459,000
Dividends declared per common share, during the period (in dollars per share)				$ 0.30			$ 0.30	$ 0.90	$ 0.90
At The Market Equity Offering Program
Class of Stock [Line Items]
Issuance of common stock (shares)				2,191,522	0	135,265
Proceeds from issuance of common stock				$ 71,600,000		$ 4,300,000
Shares issued during period, price per share				$ 33.15		$ 32.36
Subsequent Event
Class of Stock [Line Items]
Dividends declared per common share, during the period (in dollars per share)	$ 0.30
Subsequent Event | At The Market Equity Offering Program
Class of Stock [Line Items]
Issuance of common stock (shares)			2,367,837							4,694,624
Proceeds from issuance of common stock			$ 78,200,000							$ 153,700,000
Shares issued during period, price per share			$ 33.52							$ 33.31
Number of authorized shares remaining under offering program			1,174,073							1,174,073
Equity Offering
Class of Stock [Line Items]
Issuance of common stock (shares)		3,737,500
Common stock, par value (dollars per share)		$ 0.01
Shares issued, price per share		$ 31.40
Proceeds from issuance of common stock		$ 115,800,000
Minimum | At The Market Equity Offering Program
Class of Stock [Line Items]
Shares issued during period, price per share				32.62		32.01
Minimum | Subsequent Event | At The Market Equity Offering Program
Class of Stock [Line Items]
Shares issued during period, price per share			$ 33.17							$ 32.01
Maximum | At The Market Equity Offering Program
Class of Stock [Line Items]
Shares issued during period, price per share				$ 33.77		$ 32.86
Maximum | Subsequent Event | At The Market Equity Offering Program
Class of Stock [Line Items]
Shares issued during period, price per share			$ 33.74							$ 33.77