Investments (Tables)

12 Months Ended

Dec. 31, 2011

Investments, Debt and Equity Securities [Abstract]

Investments

	Cost Basis		Unrealized Gain/(Loss)			Fair Value
As of December 31, 2011
Short-term investments:
Certificates of deposit	$	269,033	$	—		$	269,033
U.S. dollar indexed bond funds	16,482		1,338			17,820
	$	285,515	$	1,338		$	286,853
Long-term investments:
Assets held in a rabbi trust	$	7,428	$	(258	)	$	7,170
As of December 31, 2010
Short-term investments:
Certificates of deposit	$	221,706	$	—		$	221,706
U.S. dollar indexed bond funds	52,714		(1,297		)	51,417
	$	274,420	$	(1,297	)	$	273,123
Long-term investments:
Assets held in a rabbi trust	$	8,068	$	95		$	8,163