Schedule Of Quarterly Financial Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2011		Sep. 30, 2011		Jun. 30, 2011		Mar. 31, 2011		Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Quarterly Financial Data [Line Items]
Total revenues	$ 302,069		$ 340,400		$ 361,518		$ 370,897		$ 354,359		$ 345,987		$ 296,855		$ 246,054		$ 1,374,884		$ 1,243,255		$ 728,239
Segment profits	92,218		118,009		128,504		133,569		138,990		136,647		111,538		89,968		472,300		477,143		221,379
Income (loss) from continuing operations	(19,977)		6,463		14,737		19,631		22,511		26,595		16,550		(18,493)		20,854		47,163
Net income (loss) available to common stockholders	$ (19,977)		$ 6,463		$ 14,737		$ 19,631		$ 22,511		$ 26,595		$ 16,550		$ (18,493)		$ 20,854		$ 47,163		$ (43,563)
Basic earnings per common share, Net income (loss) available to common stockholders	$ (0.49)	[1]	$ 0.16	[1]	$ 0.36	[1]	$ 0.48	[1]	$ 0.55	[1]	$ 0.66	[1]	$ 0.41	[1]	$ (0.46)	[1]	$ 0.51	[1]	$ 1.17	[1]	$ (1.10)
Diluted earnings per common share, Net income (loss) available to common stockholders	$ (0.49)	[1]	$ 0.16	[1]	$ 0.36	[1]	$ 0.47	[1]	$ 0.54	[1]	$ 0.64	[1]	$ 0.40	[1]	$ (0.46)	[1]	$ 0.51	[1]	$ 1.14	[1]	$ (1.10)
Weighted average common shares outstanding, Basic	39,893,000		40,227,000		41,154,000		40,758,000		40,658,000		40,451,000		40,356,000		39,884,000		40,505,555		40,375,013		39,714,053
Weighted average common shares outstanding, Diluted	40,127,000		40,441,000		41,426,000		41,629,000		41,307,000		41,396,000		41,336,000		39,884,000		41,275,293		41,536,629		39,684,231

[1] The sum of individual quarterly net income per share may not agree to the total for the year due to each period's computation being based on the weighted average number of common shares outstanding during each period.