Shareholders' Equity, Noncontrolling Interests and Other Comprehensive Income - Noncontrolling Interest (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	$ 648,440
Net income (loss)	(4,160)	$ 19,971
Conversion of Common OP Units to Common Shares by limited partners of the Operating Partnership	0	0
Other comprehensive income - unrealized loss on valuation of swap agreements	5,653	118
Reclassification of realized interest on swap agreements	363	963
Noncontrolling interest contributions		20,269
Noncontrolling interest distributions	(695)	(3,822)
Employee Long-term Incentive Plan Unit Awards	3,811	4,235
Rebalancing adjustment	0	$ 0
Ending Balance	$ 639,998
Distributions declared (in dollars per share)	$ 0.27	$ 0.26
Conversion of Common OP Units to Common Shares by limited partners of the Operating Partnership (in shares)	36,126		24,860
LTIP Units
Increase (Decrease) in Stockholders' Equity [Roll Forward]
LTIP units outstanding (in shares)	2,619,872		2,274,147
Operating Partnership, as General Partner or Managing Member
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Series A Preferred OP Units (in shares)	3,328,873		3,328,873
Operating Partnership, as General Partner or Managing Member | Series A Preferred Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Series A Preferred OP Units (in shares)	188		188
Operating Partnership, as General Partner or Managing Member | Series C Preferred Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Series A Preferred OP Units (in shares)	136,593		136,593
Noncontrolling Interests
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	$ 648,440	$ 589,548
Distributions declared of $0.27 and $0.26 per Common OP Unit for three months ended March 31, 2018 and 2017, respectively	(1,721)	(1,617)
Net income (loss)	(11,579)	4,340
Conversion of Common OP Units to Common Shares by limited partners of the Operating Partnership	(642)	(438)
Other comprehensive income - unrealized loss on valuation of swap agreements	1,160	(296)
Reclassification of realized interest on swap agreements	94	141
Noncontrolling interest contributions		20,269
Noncontrolling interest distributions	(695)	(3,822)
Employee Long-term Incentive Plan Unit Awards	3,716	4,141
Rebalancing adjustment	1,225	5,693
Ending Balance	639,998	617,959
Noncontrolling Interests | Restatement Adjustment
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Ending Balance	1,225
Noncontrolling Interests | Noncontrolling Interests in Partially-Owned Affiliates
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	545,519	494,126
Distributions declared of $0.27 and $0.26 per Common OP Unit for three months ended March 31, 2018 and 2017, respectively	0	0
Net income (loss)	(12,191)	3,278
Conversion of Common OP Units to Common Shares by limited partners of the Operating Partnership	0	0
Other comprehensive income - unrealized loss on valuation of swap agreements	886	(317)
Reclassification of realized interest on swap agreements	84	92
Noncontrolling interest contributions		20,269
Noncontrolling interest distributions	(695)	(3,822)
Employee Long-term Incentive Plan Unit Awards	0	0
Rebalancing adjustment		0
Ending Balance	533,603	513,626
Noncontrolling Interests | Noncontrolling Interests in Partially-Owned Affiliates | Restatement Adjustment
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Ending Balance	0
Noncontrolling Interests | Operating Partnership, as General Partner or Managing Member
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	102,921	95,422
Distributions declared of $0.27 and $0.26 per Common OP Unit for three months ended March 31, 2018 and 2017, respectively	(1,721)	(1,617)
Net income (loss)	612	1,062
Conversion of Common OP Units to Common Shares by limited partners of the Operating Partnership	(642)	(438)
Other comprehensive income - unrealized loss on valuation of swap agreements	274	21
Reclassification of realized interest on swap agreements	10	49
Noncontrolling interest contributions		0
Noncontrolling interest distributions	0	0
Employee Long-term Incentive Plan Unit Awards	3,716	4,141
Rebalancing adjustment		5,693
Ending Balance	106,395	$ 104,333
Noncontrolling Interests | Operating Partnership, as General Partner or Managing Member | Restatement Adjustment
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Ending Balance	$ 1,225