Noncontrolling Interest (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016	Dec. 31, 2015
Noncontrolling interest
Noncontrolling interest ownership percentage	4.30%		4.30%		4.30%	4.90%
LTIP Units | 2011 Equity Incentive Plan
Summary of nonvested share-based compensation activity
Unvested at beginning of period (in shares)			403,423	534,910	534,910
Granted (in shares)			126,239		176,396
Vested (in shares)	(45,204)	(45,874)	(112,874)	(216,151)	(307,883)
Forfeited (in shares)			0		0
Unvested at end of period (in shares)	416,788		416,788		403,423
Fair value of shares vested	$ 1,248	$ 1,092	$ 2,911	$ 4,181
Noncontrolling Interest - Unit holders in Operating Partnership
Noncontrolling interest
Units outstanding, balance at beginning of period (in units)			3,633,881	3,525,977	3,525,977
Granted/Issued (in units)			814,066		176,396
Forfeitures (in units)			0		0
Limited Partners' Capital Account, Units, Converted			0		0
Redemptions from Other Common Units to common stock (in units)			(297,006)		(68,492)
Units outstanding, balance at end of period (in units)	4,150,941		4,150,941		3,633,881
LTIP Units | Noncontrolling Interest - Unit holders in Operating Partnership
Noncontrolling interest
Units outstanding, balance at beginning of period (in units)			1,576,516	1,610,105	1,610,105
Granted/Issued (in units)			126,239		176,396
Forfeitures (in units)			0		0
Limited Partners' Capital Account, Units, Converted			227,831		209,985
Redemptions from Other Common Units to common stock (in units)			0		0
Units outstanding, balance at end of period (in units)	1,474,924		1,474,924		1,576,516
Other Common Units | Noncontrolling Interest - Unit holders in Operating Partnership
Noncontrolling interest
Units outstanding, balance at beginning of period (in units)			2,057,365	1,915,872	1,915,872
Granted/Issued (in units)			687,827		0
Forfeitures (in units)			0		0
Limited Partners' Capital Account, Units, Converted			(227,831)		(209,985)
Redemptions from Other Common Units to common stock (in units)			(297,006)		(68,492)
Units outstanding, balance at end of period (in units)	2,676,017		2,676,017		2,057,365