Consolidated Statements Of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash flows from operating activities:
Net income	$ 150,314,000	$ 103,052,000	$ 107,182,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	53,163,000	38,078,000	20,658,000
Amortization	3,472,000	2,611,000	247,000
Straight-line rental income	(24,623,000)	(16,463,000)	(6,560,000)
Non-cash interest income on construction loan	(411,000)	0	0
Unamortized debt premium written off	0	(1,655,000)	0
Write-off of debt issuance costs	0	2,145,000	416,000
Loan and realty losses (recoveries), net	491,000	0	(1,976,000)
Gain on sale of real estate	(1,126,000)	0	(22,258,000)
Gain on purchase liability settlement	0	0	3,256,000
Net realized gains on sales of marketable securities	(23,529,000)	0	0
Share-based compensation	2,134,000	2,020,000	2,339,000
Income from equity-method investee	1,767,000	71,000	(324,000)
Change in operating assets and liabilities:
Equity-method investment and other assets	216,000	(2,334,000)	(659,000)
Accounts payable and accrued expenses	1,038,000	1,448,000	2,495,000
Deferred income	2,501,000	(2,830,000)	1,937,000
Net cash provided by operating activities	164,425,000	126,143,000	104,193,000
Cash flows from investing activities:
Investment in mortgage and other notes receivable	(92,249,000)	(4,447,000)	(11,082,000)
Collection of mortgage and other notes receivable	21,495,000	1,456,000	18,976,000
Investment in real estate	(106,315,000)	(520,505,000)	(635,971,000)
Investment in real estate development	(14,641,000)	(8,455,000)	(11,926,000)
Investment in renovations of existing real estate	(3,157,000)	(4,211,000)	(6,773,000)
Payments into facility repair escrows	0	(1,554,000)	0
Payment of real estate purchase liability	0	(2,600,000)	0
Proceeds from disposition of real estate properties	9,593,000	0	20,952,000
Purchases of marketable securities	(8,458,000)	0	0
Proceeds from sales of marketable securities	57,406,000	0	0
Net cash used in investing activities	136,326,000	540,316,000	625,824,000
Cash flows from financing activities:
Net change in borrowings under revolving credit facilities	(340,000,000)	207,000,000	103,000,000
Proceeds from convertible senior notes	0	200,000,000	0
Proceeds from issuance of secured debt	78,084,000	38,007,000	0
Borrowings on term loan	325,000,000	130,000,000	330,000,000
Payments of term loans	(742,000)	(328,515,000)	(99,655,000)
Debt issuance costs	(2,608,000)	(8,443,000)	(5,867,000)
Proceeds from equity offering, net	49,114,000	270,798,000	282,542,000
Proceeds from exercise of stock options	(1,000)	0	(146,000)
Distributions to noncontrolling interest	(2,292,000)	(2,049,000)	(1,250,000)
Dividends paid to stockholders	(124,657,000)	(100,650,000)	(85,145,000)
Net cash provided by (used in) financing activities	(18,100,000)	406,148,000	523,771,000
(Decrease) increase in cash and cash equivalents	9,999,000	(8,025,000)	2,140,000
Cash and cash equivalents, beginning of year	3,287,000	11,312,000	9,172,000
Cash and cash equivalents, end of year	13,286,000	3,287,000	11,312,000
Supplemental disclosure of cash flow information:
Interest Paid	31,289,000	22,172,000	7,964,000
Supplemental schedule of non-cash investing and financing activities:
Settlement of mortgage note by real estate acquisition	0	0	13,741,000
Lease escrow deposits	0	0	22,775,000
Escrow deposit for tax deferred exchange	0	0	23,813,000
Tax deferred exchange funds applied to investment in real estate	0	23,813,000	0
Conditional consideration in asset acquisition	750,000	3,000,000	1,600,000
Settlement of contingent asset acquisition liability	(3,000,000)	0	0
Accounts payable increase due to investments in real estate	1,076,000	2,091,000	3,086,000
Accounts payable increase due to escrow deposits	0	2,062,000	0
Reclass of note balance into real estate investment	255,000	0	0
Assumption of debt in real estate acquisition	0	7,858,000	80,528,000
Assignment of net assets in equity-method investee	0	0	817,000
Conversion of investment in preferred stock to common	$ 38,132,000	$ 0	$ 0