Condensed Consolidated Statements of Cash Flows (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Operating Activities
Net cash provided by (used in) operating activities	$ 74,709	$ 67,128
Investing Activities
Principal received on loans receivable	9,507	2,898
Proceeds from sales of real estate	34,100
Investments in loans receivable	(1,293)	(4,398)
Construction in progress and other	(35,920)	(12,297)
Net cash provided by (used in) investing activities	(600,106)	(222,710)
Financing activities
Revolving credit facilities, net	35,400	39,600
Additions to term debt	300,000	450,000
Payments of term debt	(171)	(237,810)
Distributions paid	(76,770)	(67,194)
Sale of common stock, net	220,107
Lease deposits and other obligations to tenants	(13,391)	7,613
Debt issuance costs paid and other financing activities	(6,341)	(20,667)
Net cash provided by (used in) financing activities	458,834	171,542
Increase (decrease) in cash and cash equivalents for period	(66,563)	15,960
Cash and cash equivalents at beginning of period	102,726	98,408
Cash and cash equivalents at end of period	36,163	114,368
Parent
Operating Activities
Net cash provided by (used in) operating activities	16	(124)
Investing Activities
Investments in and advances to subsidiaries	(143,554)	67,126
Net cash provided by (used in) investing activities	(143,554)	67,126
Financing activities
Distributions paid	(76,569)	(67,002)
Sale of common stock, net	220,107
Net cash provided by (used in) financing activities	143,538	(67,002)
Subsidiary Issuers
Operating Activities
Net cash provided by (used in) operating activities	(38,780)	(26,727)
Investing Activities
Investments in and advances to subsidiaries	(540,016)	(89,763)
Investments in loans receivable		(205)
Construction in progress and other	(59)
Net cash provided by (used in) investing activities	(540,075)	(89,968)
Financing activities
Revolving credit facilities, net	75,000
Additions to term debt	300,000	450,000
Payments of term debt		(229,271)
Distributions paid	(76,770)	(67,194)
Sale of common stock, net	220,107
Debt issuance costs paid and other financing activities	(6,341)	(20,530)
Net cash provided by (used in) financing activities	511,996	133,005
Increase (decrease) in cash and cash equivalents for period	(66,859)	16,310
Cash and cash equivalents at beginning of period	101,230	96,822
Cash and cash equivalents at end of period	34,371	113,132
Subsidiary Guarantors
Operating Activities
Net cash provided by (used in) operating activities	114,073	86,364
Investing Activities
Cash paid for acquisitions and other related investments	(410,000)	(191,625)
Principal received on loans receivable	5,491
Proceeds from sales of real estate	800
Investments in and advances to subsidiaries	377,472	81,565
Investments in loans receivable		(3,314)
Construction in progress and other	(34,349)	(12,297)
Net cash provided by (used in) investing activities	(60,586)	(125,671)
Financing activities
Revolving credit facilities, net	(39,600)	39,600
Payments of term debt		(8,443)
Lease deposits and other obligations to tenants	(13,731)	8,140
Net cash provided by (used in) financing activities	(53,331)	39,307
Increase (decrease) in cash and cash equivalents for period	156
Cash and cash equivalents at beginning of period	1,409
Cash and cash equivalents at end of period	1,565
Non-Guarantor Subsidiaries
Operating Activities
Net cash provided by (used in) operating activities	(600)	7,615
Investing Activities
Cash paid for acquisitions and other related investments	(196,500)	(17,288)
Principal received on loans receivable	4,016	2,898
Proceeds from sales of real estate	33,300
Investments in and advances to subsidiaries	162,560	8,074
Investments in loans receivable	(1,293)	(879)
Construction in progress and other	(1,512)
Net cash provided by (used in) investing activities	571	(7,195)
Financing activities
Payments of term debt	(171)	(106)
Lease deposits and other obligations to tenants	340	(527)
Debt issuance costs paid and other financing activities		(137)
Net cash provided by (used in) financing activities	169	(770)
Increase (decrease) in cash and cash equivalents for period	140	(350)
Cash and cash equivalents at beginning of period	87	1,586
Cash and cash equivalents at end of period	227	1,236
Eliminations
Investing Activities
Investments in and advances to subsidiaries	143,538	(67,002)
Net cash provided by (used in) investing activities	143,538	(67,002)
Financing activities
Distributions paid	76,569	(67,002)
Sale of common stock, net	(220,107)
Net cash provided by (used in) financing activities	(143,538)	(67,002)
Total Consolidated
Operating Activities
Net cash provided by (used in) operating activities	74,709	67,128
Investing Activities
Cash paid for acquisitions and other related investments	(606,500)	(208,913)
Principal received on loans receivable	9,507	2,898
Proceeds from sales of real estate	34,100
Investments in loans receivable	(1,293)	(4,398)
Construction in progress and other	(35,920)	(12,297)
Net cash provided by (used in) investing activities	(600,106)	(222,710)
Financing activities
Revolving credit facilities, net	35,400	39,600
Additions to term debt	300,000	450,000
Payments of term debt	(171)	(237,810)
Distributions paid	(76,770)	(67,194)
Sale of common stock, net	220,107
Lease deposits and other obligations to tenants	(13,391)	7,613
Debt issuance costs paid and other financing activities	(6,341)	(20,667)
Net cash provided by (used in) financing activities	458,834	171,542
Increase (decrease) in cash and cash equivalents for period	(66,563)	15,960
Cash and cash equivalents at beginning of period	102,726	98,408
Cash and cash equivalents at end of period	$ 36,163	$ 114,368