Stockholders' Equity (Stock Transactions - Narrative) (Details) $ / shares in Units, $ in Thousands		3 Months Ended		9 Months Ended		10 Months Ended
	Nov. 03, 2015 $ / shares	Sep. 30, 2015 investment_bank $ / shares shares	Sep. 30, 2014 $ / shares	Sep. 30, 2015 USD ($) investment_bank $ / shares shares	Sep. 30, 2014 USD ($) $ / shares	Oct. 30, 2015 USD ($) $ / shares shares
Class of Stock [Line Items]
Net proceeds from issuance of common stock | $				$ 41,757	$ 52,712
Dividends per share paid to common stockholders (in dollars per share)				$ 0.90
Dividends per share declared to common stockholders (in dollars per share)		$ 0.30	$ 0.30	$ 0.90	$ 0.90
At The Market Equity Offering Program [Member]
Class of Stock [Line Items]
Issuance of common stock (shares) | shares				1,494,914
Net proceeds from issuance of common stock | $				$ 40,800
Number of investment banks in sales agreements | investment_bank		4		4
Shares authorized to be sold under the program | shares		9,000,000		9,000,000
Number of authorized shares remaining under offering program | shares		723,304		723,304
Subsequent Event [Member]
Class of Stock [Line Items]
Dividends per share declared to common stockholders (in dollars per share)	$ 0.30
Subsequent Event [Member] | At The Market Equity Offering Program [Member]
Class of Stock [Line Items]
Issuance of common stock (shares) | shares						1,658,335
Net proceeds from issuance of common stock | $						$ 45,000
Minimum [Member] | At The Market Equity Offering Program [Member]
Class of Stock [Line Items]
Issuance of common stock (price per share)				$ 25.00
Minimum [Member] | Subsequent Event [Member] | At The Market Equity Offering Program [Member]
Class of Stock [Line Items]
Issuance of common stock (price per share)						$ 25.00
Maximum [Member] | At The Market Equity Offering Program [Member]
Class of Stock [Line Items]
Issuance of common stock (price per share)				29.15
Maximum [Member] | Subsequent Event [Member] | At The Market Equity Offering Program [Member]
Class of Stock [Line Items]
Issuance of common stock (price per share)						29.15
Weighted Average [Member] | At The Market Equity Offering Program [Member]
Class of Stock [Line Items]
Issuance of common stock (price per share)				$ 27.69
Weighted Average [Member] | Subsequent Event [Member] | At The Market Equity Offering Program [Member]
Class of Stock [Line Items]
Issuance of common stock (price per share)						$ 27.54