Investment Activity (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Schedule Of Equity And Other Investments [Line Items]
Beginning balance, equity and other investments	$ 9,608	$ 13,203	$ 14,913	$ 18,385
Investment income	5,391	5,453	3,035	2,921
Distributions from investee	(1,351)	(1,400)	(4,300)	(4,050)
Ending balance at June 30, equity and other investments	13,648	17,256	13,648	17,256
Scarborough
Schedule Of Equity And Other Investments [Line Items]
Beginning balance, equity method investments	7,905	8,023	13,210	13,205
Investment income	5,391	5,453	3,035	2,921
Distributions from investee	(1,351)	(1,400)	(4,300)	(4,050)
Ending balance at June 30, equity method investments	11,945	12,076	11,945	12,076
TRA Preferred Stock
Schedule Of Equity And Other Investments [Line Items]
Beginning balance, cost method investments	1,703	5,180	1,703	5,180
Investment income
Distributions from investee
Ending balance at June 30, cost method investments	$ 1,703	$ 5,180	$ 1,703	$ 5,180