CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash flows from operating activities:
Net income	$ 70,205,000	$ 79,383,000	$ 46,909,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	68,472,000	63,079,000	43,332,000
Non-cash interest income adjustments	582,000	626,000	325,000
Amortization of deferred financing costs	5,040,000	5,143,000	4,045,000
Stock-based compensation expense	7,496,000	6,123,000	9,851,000
Amortization of debt discount (premium)	109,000	103,000	(10,000)
Loss on extinguishment of debt	556,000	0	1,576,000
Straight-line rental income adjustments	(21,984,000)	(24,320,000)	(19,821,000)
Provision for doubtful accounts and loan losses	5,543,000	12,842,000	3,594,000
Change in fair value of contingent consideration	(1,526,000)	(1,550,000)	(1,560,000)
Gain on consolidation	0	(710,000)	0
Net loss (gain) on sales of real estate	6,122,000	161,000	(3,914,000)
Impairment of real estate	29,811,000	0	0
Changes in operating assets and liabilities:
Prepaid expenses and other assets	(1,452,000)	(22,794,000)	(7,993,000)
Accounts payable and accrued liabilities	11,462,000	6,977,000	12,635,000
Restricted cash	(3,697,000)	(3,962,000)	(3,632,000)
Net cash provided by operating activities	176,739,000	121,101,000	85,337,000
Cash flows from investing activities:
Acquisitions of real estate	(153,579,000)	(461,330,000)	(771,479,000)
Origination and fundings of loans receivable	(9,675,000)	(49,687,000)	(66,397,000)
Origination and fundings of preferred equity investments	(7,348,000)	(12,804,000)	(15,486,000)
Additions to real estate	(1,003,000)	(3,689,000)	(1,471,000)
Repayment of loans receivable	215,962,000	5,803,000	1,097,000
Release of contingent consideration held in escrow	0	5,240,000	0
Net proceeds from sale of real estate	98,006,000	27,241,000	27,264,000
Net cash (used in) provided by investing activities	142,363,000	(489,226,000)	(826,472,000)
Cash flows from financing activities:
Proceeds from issuance of senior unsecured notes	0	0	499,250,000
Principal payments on senior unsecured notes	0	0	(211,250,000)
Net (repayments of) proceeds from revolving credit facility	(229,000,000)	187,000,000	132,500,000
Proceeds from term loan	69,360,000	73,242,000	0
Proceeds from mortgage notes	0	28,735,000	57,703,000
Principal payments on mortgage notes	(14,768,000)	(3,132,000)	(89,110,000)
Payments of deferred financing costs	(5,937,000)	(1,452,000)	(19,131,000)
Contributions by noncontrolling interests	0	179,000	0
Issuance of common stock, net	(1,289,000)	139,403,000	510,147,000
Dividends paid on common and preferred stock	(119,264,000)	(109,897,000)	(81,489,000)
Net cash provided by (in used) financing activities	(300,898,000)	314,078,000	798,620,000
Net increase (decrease) in cash and cash equivalents	18,204,000	(54,047,000)	57,485,000
Effect of foreign currency translation on cash and cash equivalents	25,000	(312,000)	0
Cash and cash equivalents, beginning of period	7,434,000	61,793,000	4,308,000
Cash and cash equivalents, end of period	25,663,000	7,434,000	61,793,000
Supplemental disclosure of cash flow information:
Interest paid	59,234,000	53,875,000	34,468,000
Supplemental disclosure of non-cash investing and financing activities:
Assumption of mortgage indebtedness	0	30,456,000	14,102,000
Increase in real estate investments due to variable interest consolidation	0	10,700,000	0
Real estate acquired through loan receivable foreclosure	10,100,000	0	0
Decrease in loans receivable and preferred equity due to variable interest consolidation	0	(8,615,000)	0
Repayment of preferred equity investments	0	0	6,949,000
Decrease in loans receivables/increase in real estate	$ 0	$ 0	$ 16,832,000