Capital Stock (Details)													1 Months Ended	12 Months Ended
	Jan. 12, 2016 $ / shares	Dec. 31, 2015 USD ($) $ / shares shares	Oct. 13, 2015 $ / shares	Sep. 30, 2015	Jul. 14, 2015 $ / shares	Jun. 30, 2015	Apr. 10, 2015 $ / shares	Mar. 31, 2015	Jan. 12, 2015 $ / shares	Oct. 10, 2014 $ / shares	Jul. 10, 2014 $ / shares	Apr. 10, 2014 $ / shares	Jan. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2015 USD ($) vote $ / shares shares	Dec. 31, 2014 USD ($) $ / shares shares	Nov. 30, 2014 USD ($)
Dividends Payable [Line Items]
Common stock, shares authorized | shares		400,000,000												400,000,000	400,000,000
Common stock, par value (in dollars per share) | $ / shares		$ 0.01												$ 0.01	$ 0.01
Common stock votes | vote														1
Stock issued during period, value, new issues | $														$ 7,790,000	$ 63,062,000
Payment Date			Oct. 13, 2015		Jul. 14, 2015		Apr. 10, 2015		Jan. 12, 2015	Oct. 10, 2014	Jul. 10, 2014	Apr. 10, 2014
Record Date		Dec. 31, 2015		Sep. 30, 2015		Jun. 30, 2015		Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014
Dividends per common share (in dollars per share) | $ / shares			$ 0.1250		$ 0.1250		$ 0.125		$ 0.1025	$ 0.1025	$ 0.1025	$ 0.1025
Preferred stock, shares authorized | shares		10,000,000												10,000,000	10,000,000
Preferred stock, par value (in dollars per share) | $ / shares		$ 0.01												$ 0.01	$ 0.01
Preferred stock, shares outstanding | shares		0												0	0
Operating partnership units option to redeem for common stock														1
Subsequent Event
Dividends Payable [Line Items]
Payment Date	Jan. 12, 2016
Dividends per common share (in dollars per share) | $ / shares	$ 0.125
Unaffiliated Third Parties
Dividends Payable [Line Items]
Units of partnership interest, amount | shares		0												0	0
Common Stock
Dividends Payable [Line Items]
Aggregate offering price | $														$ 200,000,000
Common stock sold in offering | shares													524,606	524,606	4,217,560
Share price of common stock sold | $ / shares													$ 15.18		$ 15.12
Stock issued during period, value, new issues | $													$ 7,800,000	$ 5,000	$ 42,000
Remaining amount under ATM program | $		$ 128,300,000												$ 128,300,000
Amount authorized to be repurchased | $																$ 150,000,000