Organization, Basis of Presentation and Summary of Significant Accounting Policies - Narrative (Details) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017 USD ($) property	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2017 USD ($) segment property	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Number of reportable segments | segment									3
Rental income									$ 198,941	$ 152,814	$ 158,632
Depreciation and amortization									104,934	70,011	60,751
Interest expense									58,978	34,645	37,297
Equity in earnings (losses) of unconsolidated affiliates									23,371	39,449	37,330
Net income (loss)	$ 24,944	$ 13,285	$ 6,108	$ 19,971	$ 34,236	$ 326	$ 26,155	$ 73,875	64,308	134,592	149,970
Net loss (income) attributable to noncontrolling interests	4,032	$ 418	$ (5,952)	$ 4,340	14,415	$ (5,786)	$ 8,237	$ 44,950	2,838	61,816	84,262
Additional paid-in capital	1,596,514				1,594,926				1,596,514	1,594,926
Noncontrolling interests	648,440				589,548				648,440	589,548
Deferred rent receivables	37,300				34,900				37,300	34,900
Allowance for doubtful accounts receivable	5,900				5,700				5,900	5,700
Adjustment to deferred tax assets									2,000
Lease future payment obligation	207,167								207,167
Capitalized internal leasing costs	$ 1,000				1,100				1,000	1,100	1,400
Net Cash Provided by (Used in) Investing Activities									10,082	(610,970)	(354,503)
Acquisition related costs									2,100	8,200
Net Cash Provided by (Used in) Operating Activities									$ 119,833	$ 111,760	113,598
Buildings
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Property, plant and equipment, useful life									40 years
Building Improvements
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Property, plant and equipment, useful life									15 years
Furniture and fixtures | Minimum
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Property, plant and equipment, useful life									5 years
Furniture and fixtures | Maximum
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Property, plant and equipment, useful life									20 years
Operating Partnership, as General Partner or Managing Member
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Equity interest held by Operating Partnership									95.00%	95.00%
Remaining funds rate of distribution to operating partnership (in percent)	20.00%								20.00%
Equity in earnings (losses) of unconsolidated affiliates									$ 23,371	$ 39,449	37,330
Institutional Investors
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Remaining funds rate of distribution to all partners (in percent)	80.00%								80.00%
Restatement Adjustment
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Rental income										(2,100)
Depreciation and amortization										1,700
Interest expense										700
Equity in earnings (losses) of unconsolidated affiliates										200
Net income (loss)					(4,200)					(4,200)
Net loss (income) attributable to noncontrolling interests					(1,600)					(1,600)
Additional paid-in capital					35,700					35,700	31,800
Noncontrolling interests					$ (35,700)					(35,700)	$ (31,800)
Pro Forma | Accounting Standards Update 2016-15
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Net Cash Provided by (Used in) Investing Activities									$ 6,300	0
Net Cash Provided by (Used in) Operating Activities									$ (6,300)	0
Core Portfolio
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Number of retail properties | property	118								118
Properties owned percentage	100.00%								100.00%
Acquisition related costs									$ 1,200	5,500
Opportunity Funds
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Number of retail properties | property	58								58
Core Portfolio and Opportunity Funds
Organization, Consolidation and Presentation of Financial Statements [Line Items]
Number of retail properties | property	176								176
Acquisition related costs									$ 2,100	$ 8,200