Investments and Fair Value Measurements (Cost and Fair Value of Investments Classified by Maturity) (Details) (USD $)	Mar. 31, 2013	Dec. 31, 2012
Available-for-sale Securities, Debt Maturities [Abstract]
Available-for-sale securities, Due in one year or less, Cost	$ 49,988,000	$ 87,599,000
Available-for-sale securities, Due in one year or less, Fair Vlaue	49,710,000	86,784,000
Available-for-sale securities, Due in one to two years, Cost	0	6,846,000
Available-for-sale securities, Due in one to two years, Fair Value	0	6,808,000
Available-for-sale securities, Equity securities, exchange-traded funds, and mutual funds, Cost	17,874,000	30,112,000
Available-for-sale securities, Equity securities, exchange-traded funds, and mutual funds, Fair Value	20,483,000	32,194,000
Available-for-sale securities, Cost	67,862,000	124,557,000
Available-for-sale securities, Current	70,193,000	125,786,000
Held-to-maturity Securities, Debt Maturities [Abstract]
Held-to-maturity securities, Due in one year or less, Cost	26,403,000	26,352,000
Held-to-maturity securities, Due within one year or less, Fair Value	26,403,000	26,352,000
Held-to-maturity securities, Due in one to three years, Cost	5,000	5,000
Held-to-maturity securities, Due in one to three years, Fair Value	5,000	5,000
Held-to-maturity securities, Cost	26,408,000	26,357,000
Held-to-maturity securities, Current	26,408,000	26,357,000
Certificate of deposit held as collateral against Australia office lease	$ 1,500,000