Earnings Per Common Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Shares Outstanding
Weighted average common shares - basic	42,702	41,405	42,584	40,634
Weighted average partnership units outstanding	0	1,781	1,709	1,859
Effect of dilutive securities	0	35	53	74
Weighted average common shares - diluted	42,702	43,221	44,346	42,567
Calculation of Earnings per Share - basic
Income (Loss) from Continuing Operations, Including Portion Attributable to Noncontrolling Interest	$ 16,619	$ 15,134	$ 53,746	$ 43,895
Income from continuing operations attributable to noncontrolling interests	(645)	(466)	(1,535)	(1,731)
Income from continuing operations allocated to unvested restricted shares	(14)	(12)	(47)	(39)
Adjusted Income (Loss) from Continuing Operations Available for Common Shareholders, Basic	15,960	14,656	52,164	42,125
Income from discontinued operations	(29,437)	(16,944)	(75,343)	(42,723)
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Noncontrolling Interest	(1,127)	(746)	(3,001)	(1,971)
Income from discontinued operations allocated to unvested restricted shares	(24)	(13)	(66)	(38)
Adjusted Income (Loss) from Discontinued Operations Available for Common Shareholders, Basic	28,286	16,185	72,276	40,714
Weighted average common shares - basic	42,702	41,405	42,584	40,634
Earnings per share - basic	$ 1.04	$ 0.74	$ 2.92	$ 2.04
Income (Loss) from Continuing Operations Attributable to Noncontrolling Interest, Diluted	(645)	0	0	0
Calculation of Earnings per Share - diluted
Net income attributable to noncontrolling interests	1,772	1,212	4,536	3,702
Weighted average common shares - diluted	42,702	43,221	44,346	42,567
Earnings per share - diluted	$ 1.04	$ 0.74	$ 2.91	$ 2.03
Income from Continuing Operations Allocated to Unvested Restricted Shares, Diluted	(14)	0	0	0
Income (Loss) from Discontinued Operations Attributable to Noncontrolling Interest, Diluted	(1,127)	0	0	0
Income from Discontinued Operations Allocated to Unvested Restricted Shares, Diluted	(23)	0	0	0
Adjusted Income (Loss) from Continuing Operations Available for Common Shareholders, Diluted	15,960	15,134	53,746	43,895
Adjusted Income (Loss) from Discontinued Operations Available for Common Shareholders, Diluted	$ 28,287	$ 16,944	$ 75,343	$ 42,723