Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Redeemable Noncontrolling Interests [Abstract]
Net unrealized gain (loss) on hedging agreements	$ 371	$ 377
Net unrealized gain on available-for-sale securities	344	328
Accumulated other comprehensive income (loss)	715	705
Shareholders' Equity [Abstract]
Net unrealized gain (loss) on hedging agreements	(3,208)	(2,628)
Net unrealized gain on available-for-sale securities	7,595	6,053
Accumulated other comprehensive income (loss)	4,387	3,425
Noncontrolling Interests [Abstract]
Net unrealized gain (loss) on hedging agreements	(3,617)	(3,488)
Net unrealized loss on available-for-sale securities	2,158	1,775
Accumulated other comprehensive income (loss)	(1,459)	(1,713)
Total Accumulated Other Comprehensive Income [Abstract]
Total unrealized gain (loss) on hedging agreements	(6,454)	(5,739)
Total unrealized gain on available-for-sale securities	10,097	8,156
Total accumulated other comprehensive income (loss)	$ 3,643	$ 2,417