Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Redeemable Noncontrolling Interests [Abstract]
Net unrealized gain (loss) on hedging agreements	$ 373	$ 377
Net unrealized gain on available-for-sale securities	340	328
Accumulated other comprehensive income (loss)	713	705
Shareholders' Equity [Abstract]
Net unrealized gain (loss) on hedging agreements	(3,013)	(2,628)
Net unrealized gain on available-for-sale securities	7,159	6,053
Accumulated other comprehensive income (loss)	4,146	3,425
Noncontrolling Interests [Abstract]
Net unrealized gain (loss) on hedging agreements	(3,580)	(3,488)
Net unrealized loss on available-for-sale securities	2,076	1,775
Accumulated other comprehensive income (loss)	(1,504)	(1,713)
Total Accumulated Other Comprehensive Income [Abstract]
Total unrealized gain (loss) on hedging agreements	(6,220)	(5,739)
Total unrealized gain on available-for-sale securities	9,575	8,156
Total accumulated other comprehensive income (loss)	$ 3,355	$ 2,417