Shareholders' Equity, Noncontrolling Interests and Other Comprehensive Income - Noncontrolling Interest (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance	$ 589,548
Net income attributable to noncontrolling interests	(4,340)	$ (44,950)
Conversion of Common OP Units to Common Shares by limited partners of the Operating Partnership	0	0
Issuance of OP Units to acquire real estate		29,336
Acquisition of noncontrolling interests		(18,379)
Other comprehensive income - unrealized loss on valuation of swap agreements	118	(8,819)
Reclassification of realized interest on swap agreements	963	1,046
Noncontrolling interest contributions	20,269	46,343
Noncontrolling interest distributions and other reductions	(3,822)	(36,174)
Employee Long-term Incentive Plan Unit Awards	4,235	4,019
Balance	617,959		$ 589,548
Payments to noncontrolling interests	$ 6,163	$ 56,995
Distributions declared (in dollars per share)	$ 0.26	$ 0.25	$ 0.25
Limited partners' capital account, units issued and converted (in shares)	24,860		248,160
LTIP Units [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
LTIP units outstanding (in shares)	2,265,852	1,979,882
Series A Preferred Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Limited partners' capital account, units issued and converted (in shares)	1,392
Series C Preferred Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Series A Preferred OP Units (in shares)	141,593	141,593
Fund II [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Additional ownership interest acquired		8.30%
Payments to noncontrolling interests		$ 18,400
Equity Interest Held By Operating Partnership (b)		28.33%
Operating Partnership, as General Partner or Managing Member [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Series A Preferred OP Units (in shares)	3,363,351	3,357,760
Equity Interest Held By Operating Partnership (b)	95.00%		95.00%
Operating Partnership, as General Partner or Managing Member [Member] | Series A Preferred Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Series A Preferred OP Units (in shares)	188	188
Operating Partnership, as General Partner or Managing Member [Member] | Series C Preferred Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Series A Preferred OP Units (in shares)	141,593	141,593
Noncontrolling Interests
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance	$ 589,548	$ 420,866	$ 420,866
Distributions declared	(1,617)	(1,473)
Net income attributable to noncontrolling interests	4,340	44,950
Conversion of Common OP Units to Common Shares by limited partners of the Operating Partnership	(438)	(5,680)
Issuance of OP Units to acquire real estate		29,336
Acquisition of noncontrolling interests		(25,948)
Other comprehensive income - unrealized loss on valuation of swap agreements	(296)	(914)
Reclassification of realized interest on swap agreements	141	145
Noncontrolling interest contributions	20,269	46,343
Noncontrolling interest distributions and other reductions	(3,822)	(36,174)
Employee Long-term Incentive Plan Unit Awards	4,141	3,811
Balance	617,959	475,262	589,548
Noncontrolling Interests | Restatement Adjustment [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance	5,693
Noncontrolling Interests | Partially-Owned Affiliates [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance	494,126	324,526	324,526
Distributions declared	0	0
Net income attributable to noncontrolling interests	3,278	42,957
Conversion of Common OP Units to Common Shares by limited partners of the Operating Partnership	0	0
Issuance of OP Units to acquire real estate		0
Acquisition of noncontrolling interests		(25,948)
Other comprehensive income - unrealized loss on valuation of swap agreements	(317)	(478)
Reclassification of realized interest on swap agreements	92	96
Noncontrolling interest contributions	20,269	46,343
Noncontrolling interest distributions and other reductions	(3,822)	(36,174)
Employee Long-term Incentive Plan Unit Awards	0	0
Balance	513,626	351,322	494,126
Noncontrolling Interests | Partially-Owned Affiliates [Member] | Restatement Adjustment [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance	0
Noncontrolling Interests | Operating Partnership, as General Partner or Managing Member [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance	95,422	96,340	96,340
Distributions declared	(1,617)	(1,473)
Net income attributable to noncontrolling interests	1,062	1,993
Conversion of Common OP Units to Common Shares by limited partners of the Operating Partnership	(438)	(5,680)
Issuance of OP Units to acquire real estate		29,336
Acquisition of noncontrolling interests		0
Other comprehensive income - unrealized loss on valuation of swap agreements	21	(436)
Reclassification of realized interest on swap agreements	49	49
Noncontrolling interest contributions	0	0
Noncontrolling interest distributions and other reductions	0	0
Employee Long-term Incentive Plan Unit Awards	4,141	3,811
Balance	104,333	$ 123,940	$ 95,422
Noncontrolling Interests | Operating Partnership, as General Partner or Managing Member [Member] | Restatement Adjustment [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance	$ 5,693