Investments and Fair Value Measurements (Cost and Fair Value of Investments Classified by Maturity) (Details) (USD $)	Sep. 30, 2012	Dec. 31, 2011
Available-for-sale Securities, Debt Maturities [Abstract]
Available-for-sale securities, Due in one year or less, Cost	$ 107,770,000	$ 155,651,000
Available-for-sale securities, Due in one year or less, Fair Vlaue	106,979,000	155,247,000
Available-for-sale securities, Due in one to two years, Cost	16,061,000	75,001,000
Available-for-sale securities, Due in one to two years, Fair Value	15,938,000	74,804,000
Available For Sale Securities Debt Maturities After Two Years Amortized Cost Basis	274,000	0
Available For Sale Securities Debit Maturities More than Two Years Fair Value	262,000	0
Available-for-sale securities, Equity securities, exchange-traded funds, and mutual funds, Cost	39,685,000	17,759,000
Available-for-sale securities, Equity securities, exchange-traded funds, and mutual funds, Fair Value	42,338,000	17,866,000
Available-for-sale securities, Cost	163,790,000	248,411,000
Available-for-sale securities, Current	165,517,000	247,917,000
Held-to-maturity Securities, Debt Maturities [Abstract]
Held-to-maturity securities, Due in one year or less, Cost	19,942,000	16,342,000
Held-to-maturity securities, Due within one year or less, Fair Value	19,942,000	16,342,000
Held-to-maturity securities, Due in one to three years, Cost	6,000	5,000
Held-to-maturity securities, Due in one to three years, Fair Value	6,000	5,000
Held-to-maturity securities, Cost	19,948,000	16,347,000
Held-to-maturity securities, Current	19,948,000	16,347,000
Certificate of deposit held as collateral against Australia office lease	$ 1,500,000	$ 1,600,000