SUMMARIZED CONDENSED CONSOLIDATING INFORMATION (Condensed Consolidating Balance Sheet) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	Jun. 30, 2013	Mar. 21, 2013	Dec. 31, 2012	Jun. 30, 2012	Dec. 31, 2011	Dec. 31, 2010
Assets
Real estate investments, net of accumulated depreciation	$ 817,228		$ 827,135
Loans receivable and other investments, net	43,069		12,017
Cash and cash equivalents	92,770		17,101	3,110	42,250	42,250
Restricted cash	5,737		4,589
Deferred tax assets	24,212		24,212
Assets held for sale, net	0		2,215
Prepaid expenses, deferred financing costs and other assets	39,083		29,613
Due from Affiliates	0		0
Investments in subsidiaries	0		0
Total assets	1,022,099		916,882
Liabilities and stockholders’ equity
Mortgage notes payable	143,129		152,322
Secured revolving credit facility	0		92,500
Senior unsecured notes payable	414,672		330,666
Accounts payable and accrued liabilities	14,519		11,694
Tax liability	24,212		24,212
Intercompany	0		0
Total liabilities	596,532		611,394
Preferred Stock, Value, Issued	58		0
Stockholders’ equity
Common stock	373		371
Additional paid-in capital	493,479		353,861
Cumulative distributions in excess of net income	(68,343)		(48,744)
Total stockholders’ equity	425,567		305,488	316,425		326,573
Total liabilities and stockholders’ equity	1,022,099		916,882
Preferred stock, par value	$ 0.01		$ 0.01
Preferred stock, shares authorized	10,000,000		10,000,000
Preferred stock, shares issued	5,750,000	5,800,000	0
Preferred stock, shares outstanding	5,750,000		0
Common stock, par value	$ 0.01		$ 0.01
Common stock, shares authorized	125,000,000		125,000,000
Common stock, shares issued	37,333,943		37,099,209
Common stock, shares outstanding	37,333,943		37,099,209
Parent Company [Member]
Assets
Real estate investments, net of accumulated depreciation	126		151
Loans receivable and other investments, net	0		0
Cash and cash equivalents	91,208		15,075	1,583		41,736
Restricted cash	0		0
Deferred tax assets	24,212		24,212
Assets held for sale, net			0
Prepaid expenses, deferred financing costs and other assets	776		1,315
Due from Affiliates	0		0
Investments in subsidiaries	367,799		351,632
Total assets	484,121		392,385
Liabilities and stockholders’ equity
Mortgage notes payable	0		0
Secured revolving credit facility			0
Senior unsecured notes payable	0		0
Accounts payable and accrued liabilities	4,560		3,281
Tax liability	24,212		24,212
Intercompany	29,782		59,404
Total liabilities	58,554		86,897
Preferred Stock, Value, Issued	58		0
Stockholders’ equity
Common stock	373		371
Additional paid-in capital	493,479		353,861
Cumulative distributions in excess of net income	(68,343)		(48,744)
Total stockholders’ equity	425,567		305,488
Total liabilities and stockholders’ equity	484,121		392,385
Issuers [Member]
Assets
Real estate investments, net of accumulated depreciation	0		0
Loans receivable and other investments, net	0		0
Cash and cash equivalents	0		0	0		0
Restricted cash	0		0
Deferred tax assets	0		0
Assets held for sale, net			0
Prepaid expenses, deferred financing costs and other assets	9,460		7,339
Due from Affiliates	284,676		227,396
Investments in subsidiaries	492,335		451,975
Total assets	786,471		686,710
Liabilities and stockholders’ equity
Mortgage notes payable	0		0
Secured revolving credit facility			0
Senior unsecured notes payable	414,672		330,666
Accounts payable and accrued liabilities	4,000		4,412
Tax liability	0		0
Intercompany	0		0
Total liabilities	418,672		335,078
Preferred Stock, Value, Issued	0		0
Stockholders’ equity
Common stock	0		0
Additional paid-in capital	292,579		292,939
Cumulative distributions in excess of net income	75,220		58,693
Total stockholders’ equity	367,799		351,632
Total liabilities and stockholders’ equity	786,471		686,710
Combined Guarantor Subsidiaries [Member]
Assets
Real estate investments, net of accumulated depreciation	649,820		655,881
Loans receivable and other investments, net	43,069		12,017
Cash and cash equivalents	0		0	0		0
Restricted cash	471		92
Deferred tax assets	0		0
Assets held for sale, net			0
Prepaid expenses, deferred financing costs and other assets	24,428		18,133
Due from Affiliates	0		0
Investments in subsidiaries	25,346		23,142
Total assets	743,134		709,265
Liabilities and stockholders’ equity
Mortgage notes payable	0		0
Secured revolving credit facility			92,500
Senior unsecured notes payable	0		0
Accounts payable and accrued liabilities	5,158		3,348
Tax liability	0		0
Intercompany	291,765		205,458
Total liabilities	296,923		301,306
Preferred Stock, Value, Issued	0		0
Stockholders’ equity
Common stock	0		0
Additional paid-in capital	324,329		321,666
Cumulative distributions in excess of net income	121,882		86,293
Total stockholders’ equity	446,211		407,959
Total liabilities and stockholders’ equity	743,134		709,265
Combined Non-Guarantor Subsidiaries [Member]
Assets
Real estate investments, net of accumulated depreciation	167,282		171,103
Loans receivable and other investments, net	0		0
Cash and cash equivalents	1,562		2,026	1,527		514
Restricted cash	5,266		4,497
Deferred tax assets	0		0
Assets held for sale, net			2,215
Prepaid expenses, deferred financing costs and other assets	4,419		2,826
Due from Affiliates	36,871		37,466
Investments in subsidiaries	0		0
Total assets	215,400		220,133
Liabilities and stockholders’ equity
Mortgage notes payable	143,129		152,322
Secured revolving credit facility			0
Senior unsecured notes payable	0		0
Accounts payable and accrued liabilities	801		653
Tax liability	0		0
Intercompany	0		0
Total liabilities	143,930		152,975
Preferred Stock, Value, Issued	0		0
Stockholders’ equity
Common stock	0		0
Additional paid-in capital	51,225		53,952
Cumulative distributions in excess of net income	20,245		13,206
Total stockholders’ equity	71,470		67,158
Total liabilities and stockholders’ equity	215,400		220,133
Elimination [Member]
Assets
Real estate investments, net of accumulated depreciation	0		0
Loans receivable and other investments, net	0
Cash and cash equivalents	0		0	0		0
Restricted cash	0		0
Deferred tax assets	0		0
Assets held for sale, net			0
Prepaid expenses, deferred financing costs and other assets	0		0
Due from Affiliates	(321,547)		(264,862)
Investments in subsidiaries	(885,480)		(826,749)
Total assets	(1,207,027)		(1,091,611)
Liabilities and stockholders’ equity
Mortgage notes payable	0		0
Senior unsecured notes payable	0		0
Accounts payable and accrued liabilities	0		0
Tax liability	0		0
Intercompany	(321,547)		(264,862)
Total liabilities	(321,547)		(264,862)
Preferred Stock, Value, Issued	0		0
Stockholders’ equity
Common stock	0		0
Additional paid-in capital	(668,133)		(668,557)
Cumulative distributions in excess of net income	(217,347)		(158,192)
Total stockholders’ equity	(885,480)		(826,749)
Total liabilities and stockholders’ equity	$ (1,207,027)		$ (1,091,611)