Comprehensive Income (Details) (USD $) In Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010
Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract]
Net income (loss)	$ (18,320)	$ 27,677	$ 75,120	$ 59,397
Other comprehensive income (loss) [Abstract]
Net unrealized gain (loss) on hedging agreements	(3,393)	1,054	(5,466)	2,569
Net unrealized gain (loss) on available-for-sale securities	(5,210)	458	(3,403)	5,354
Realized loss on sale of marketable securities	0	0	22	0
Realized loss on foreign currency translation adjustment	0	0	0	169
Net unrealized loss on foreign currency translation adjustment	0	0	0	(156)
Total other comprehensive income (loss)	(8,603)	1,512	(8,847)	7,936
Comprehensive income (loss)	(26,923)	29,189	66,273	67,333
Redeemable Noncontrolling Interests [Abstract]
Net unrealized gain (loss) on hedging agreements	378		378		422
Net unrealized gain on available-for-sale securities	303		303		331
Accumulated other comprehensive income (loss)	681		681		753
Shareholders' Equity [Abstract]
Net unrealized gain (loss) on hedging agreements	(2,585)		(2,585)		1,675
Net unrealized gain on available-for-sale securities	3,546		3,546		6,180
Accumulated other comprehensive income (loss)	961		961		7,855
Noncontrolling Interests [Abstract]
Net unrealized gain (loss) on hedging agreements	(3,476)		(3,476)		(2,315)
Net unrealized loss on available-for-sale securities	1,120		1,120		1,837
Accumulated other comprehensive income (loss)	(2,356)		(2,356)		(478)
Total Accumulated Other Comprehensive Income [Abstract]
Total unrealized gain (loss) on hedging agreements	(5,683)		(5,683)		(218)
Total unrealized gain on available-for-sale securities	4,969		4,969		8,348
Total accumulated other comprehensive income (loss)	$ (714)		$ (714)		$ 8,130