Consolidated Statements Of Cash Flows (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash flows from operating activities:
Net income	$ 107,182,000	$ 90,898,000	$ 81,132,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	20,658,000	16,981,000	11,992,000
Amortization	247,000	320,000	581,000
Straight-line rental income	(6,560,000)	(3,664,000)	(3,778,000)
Non-cash interest income on construction loan	0	0	(1,082,000)
Write-off of debt issuance costs	416,000	0	0
Loan and realty losses (recoveries), net	1,976,000	(2,195,000)	(99,000)
Gain on sale of real estate	(22,258,000)	(11,966,000)	(3,348,000)
Gain on payoff of mortgage note	0	(4,605,000)	0
Gain on purchase liability settlement	(3,256,000)	0	0
Net realized gains on sales of marketable securities	0	(30,000)	(9,899,000)
Share-based compensation	2,339,000	2,168,000	3,087,000
Change in fair value of interest rate swap agreement	0	0	1,197,000
Income from equity-method investee	(324,000)	(45,000)	0
Change in operating assets and liabilities:
Equity-method investment and other assets	(659,000)	(745,000)	(3,236,000)
Accounts payable and accrued expenses	2,495,000	(512,000)	95,000
Deferred income	1,937,000	(339,000)	212,000
Net cash provided by operating activities	104,193,000	86,266,000	76,854,000
Cash flows from investing activities:
Investment in mortgage and other notes receivable	(11,082,000)	(16,241,000)	(6,566,000)
Collection of mortgage and other notes receivable	18,976,000	17,463,000	4,540,000
Investment in real estate	(635,971,000)	(110,601,000)	(75,806,000)
Investment in real estate development	(11,926,000)	0	0
Investment in renovations of existing real estate	(6,773,000)	0	0
Receipt of earnest money deposit	0	0	525,000
Investment in unconsolidated entity	0	(8,309,000)	0
Real estate purchase deposit	0	(5,222,000)	0
Proceeds from disposition of real estate properties	20,952,000	22,975,000	8,971,000
Proceeds from sales of marketable securities	0	125,000	12,862,000
Net cash used in investing activities	(625,824,000)	(99,810,000)	(55,474,000)
Cash flows from financing activities:
Net change in borrowings under revolving credit facilities	103,000,000	(33,300,000)	59,535,000
Borrowings on term loan	330,000,000	120,000,000	50,000,000
Payments of term loans	(99,655,000)	0	(50,000,000)
Debt issuance costs	(5,867,000)	(766,000)	0
Proceeds from equity offering, net	282,542,000	0	0
Proceeds from exercise of stock options	(146,000)	2,000	(200,000)
Distributions to noncontrolling interest	(1,250,000)	(177,000)	0
Dividends paid to stockholders	(85,145,000)	(78,925,000)	(67,893,000)
Net cash provided by (used in) financing activities	523,771,000	6,830,000	(8,158,000)
(Decrease) increase in cash and cash equivalents	2,140,000	(6,714,000)	13,222,000
Cash and cash equivalents, beginning of year	9,172,000	15,886,000	2,664,000
Cash and cash equivalents, end of year	11,312,000	9,172,000	15,886,000
Supplemental schedule of non-cash investing and financing activities:
Settlement of mortgage note by real estate acquisition	13,741,000	0	0
Assumption of debt in real estate acquisition	80,528,000	19,250,000	0
Assignment of net assets in equity-method investee	$ 817,000