Condensed Consolidating Financial Information - Condensed Consolidated Statements of Cash Flows (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Operating Activities
Net cash provided by (used in) operating activities	$ 56,245	$ 44,423
Investing Activities
Cash paid for acquisitions and other related investments	(75,000)	(396,500)
Principal received on loans receivable	3,293	7,966
Net proceeds from sale of real estate	18,409	16,000
Net proceeds from sale of real estate	18,409
Investments in loans receivable	(1,300)	(1,293)
Construction in progress and other	(33,171)	(20,655)
Net cash provided by (used in) investing activities	(87,769)	(394,482)
Financing Activities
Revolving credit facilities, net	(85,000)	(89,600)
Additions to term debt		300,000
Payments of term debt	(11,124)	(114)
Distributions paid	(57,846)	(49,589)
Proceeds from sale of common shares/units, net of offering costs	172,853	220,160
Lease deposits and other obligations to tenants	1,516	383
Debt issuance costs paid and other financing activities	(114)	(6,268)
Net cash provided by (used in) financing activities	20,285	374,972
Increase (decrease) in cash and cash equivalents for period	(11,239)	24,913
Cash and cash equivalents at beginning of period	37,311	102,726
Cash and cash equivalents at end of period	26,072	127,639
Parent
Operating Activities
Net cash provided by (used in) operating activities	(35)
Investing Activities
Investments in and advances to subsidiaries	(115,106)	(170,705)
Net cash provided by (used in) investing activities	(115,106)	(170,705)
Financing Activities
Distributions paid	(57,712)	(49,455)
Proceeds from sale of common shares/units, net of offering costs	172,853	220,160
Net cash provided by (used in) financing activities	115,141	170,705
Subsidiary Issuers
Operating Activities
Net cash provided by (used in) operating activities	(29,249)	(30,512)
Investing Activities
Investments in and advances to subsidiaries	1,417	(359,319)
Construction in progress and other	(621)	(47)
Net cash provided by (used in) investing activities	796	(359,366)
Financing Activities
Revolving credit facilities, net	(85,000)	(50,000)
Additions to term debt		300,000
Payments of term debt	(11,000)
Distributions paid	(57,846)	(49,589)
Proceeds from sale of common shares/units, net of offering costs	172,853	220,160
Debt issuance costs paid and other financing activities	(114)	(6,268)
Net cash provided by (used in) financing activities	18,893	414,303
Increase (decrease) in cash and cash equivalents for period	(9,560)	24,425
Cash and cash equivalents at beginning of period	35,483	101,230
Cash and cash equivalents at end of period	25,923	125,655
Subsidiary Guarantors
Operating Activities
Net cash provided by (used in) operating activities	83,956	71,218
Investing Activities
Cash paid for acquisitions and other related investments	(75,000)	(200,000)
Principal received on loans receivable		5,491
Investments in and advances to subsidiaries	22,149	183,197
Construction in progress and other	(33,144)	(19,970)
Net cash provided by (used in) investing activities	(85,995)	(31,282)
Financing Activities
Revolving credit facilities, net		(39,600)
Lease deposits and other obligations to tenants	474	(180)
Net cash provided by (used in) financing activities	474	(39,780)
Increase (decrease) in cash and cash equivalents for period	(1,565)	156
Cash and cash equivalents at beginning of period	1,565	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	1,573	3,717
Investing Activities
Cash paid for acquisitions and other related investments		(196,500)
Principal received on loans receivable	3,293	2,475
Net proceeds from sale of real estate	18,409
Investments in and advances to subsidiaries	(23,601)	176,122
Investments in loans receivable	(1,300)	(1,293)
Construction in progress and other	594	(638)
Net cash provided by (used in) investing activities	(2,605)	(3,834)
Financing Activities
Payments of term debt	(124)	(114)
Lease deposits and other obligations to tenants	1,042	563
Net cash provided by (used in) financing activities	918	449
Increase (decrease) in cash and cash equivalents for period	(114)	332
Cash and cash equivalents at beginning of period	263	87
Cash and cash equivalents at end of period	149	419
Eliminations
Investing Activities
Investments in and advances to subsidiaries	115,141	170,705
Net cash provided by (used in) investing activities	115,141	170,705
Financing Activities
Distributions paid	57,712	49,455
Proceeds from sale of common shares/units, net of offering costs	(172,853)	(220,160)
Net cash provided by (used in) financing activities	$ (115,141)	$ (170,705)