Stockholders' Equity (Stock Transactions - Narrative) (Details)		1 Months Ended		3 Months Ended			6 Months Ended
	Aug. 04, 2020 $ / shares	Jul. 31, 2020 $ / shares shares	Jun. 30, 2020 $ / shares shares	Jun. 30, 2020 USD ($) $ / shares shares	Mar. 31, 2020 USD ($) $ / shares shares	Jun. 30, 2019 $ / shares	Jun. 30, 2020 USD ($) $ / shares shares	Jun. 30, 2019 USD ($) $ / shares	Aug. 05, 2020 USD ($)	Feb. 14, 2020 USD ($) investment_bank
Class of Stock [Line Items]
At-the-market equity offering program, authorized amount | $										$ 500,000,000.0
Net proceeds from issuance of common stock | $							$ 40,169,000	$ 120,668,000
Forward equity agreement (in shares) | shares				1,579,371			1,600,000
Proceeds from issuance of common stock, adjusted for costs to borrow | $				$ 50,000,000			$ 50,000,000.0
Stock price, per share to be subsequently sold (in USD per share)			$ 31.66	$ 31.66			$ 31.66
Dividends declared per common share, during the period (in dollars per share)				$ 0.30		$ 0.30	$ 0.60	$ 0.60
Weighted-average incremental shares of common stock excluded from the computation (shares) | shares				11,331
At the market equity offering program
Class of Stock [Line Items]
Number of investment banks included in the program | investment_bank										6
Issuance of common stock (in shares) | shares				1,071,987	196,250		1,268,237
Net proceeds from issuance of common stock | $				$ 32,900,000	$ 7,000,000.0		$ 39,900,000
Forward equity agreement (in shares) | shares			1,600,000
Subsequent event
Class of Stock [Line Items]
Forward equity agreement (in shares) | shares		764,472
Stock price, per share to be subsequently sold (in USD per share)		$ 31.84
At-the-market equity offering program, remaining authorized amount, assuming forward equity contracts settle | $									$ 385,300,000
Dividends declared per common share, during the period (in dollars per share)	$ 0.30
Minimum | At the market equity offering program
Class of Stock [Line Items]
Shares issued during period, price per share (in dollars per share)				$ 30.50	$ 33.00		$ 30.50
Maximum | At the market equity offering program
Class of Stock [Line Items]
Shares issued during period, price per share (in dollars per share)				31.29	36.15		36.15
Weighted Average | At the market equity offering program
Class of Stock [Line Items]
Shares issued during period, price per share (in dollars per share)				$ 31.08	$ 36.09		$ 31.86