Fair Value Measurements - (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012 Rate	Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Instruments, Owned, State and Municipal Government Obligations, at Fair Value	$ 68,002	$ 70,525
Available-for-sale Securities, Failed Auction, Value	319	363
Available-for-sale Securities, Fair Value Disclosure	68,321	70,888
Foreign Currency Contracts, Liability, Fair Value Disclosure	(142)	99
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	(142)	99
Financial Instruments, Owned, at Fair Value	68,179	70,987
Fair Value Input Discount Rate	2.50%
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	319	363
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)	(44)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases, Sales, Issues, Settlements	0
Fair Value, Level 3 Transfers out, Description	0
Convertible Debt	48,372
Long-term Debt, Fair Value	50,400
Fair Value Inputs Discount Rate 2	8.80%
Long-term Debt, Contingent Payment of Principal or Interest	0
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Instruments, Owned, State and Municipal Government Obligations, at Fair Value	68,002	70,525
Available-for-sale Securities, Failed Auction, Value	0	0
Available-for-sale Securities, Fair Value Disclosure	68,002	70,525
Foreign Currency Contracts, Liability, Fair Value Disclosure	(142)	99
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	(142)	99
Financial Instruments, Owned, at Fair Value	67,860	70,624
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Instruments, Owned, State and Municipal Government Obligations, at Fair Value	0	0
Available-for-sale Securities, Failed Auction, Value	0	0
Available-for-sale Securities, Fair Value Disclosure	0	0
Foreign Currency Contracts, Liability, Fair Value Disclosure	0	0
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	0	0
Financial Instruments, Owned, at Fair Value	0	0
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Instruments, Owned, State and Municipal Government Obligations, at Fair Value	0	0
Available-for-sale Securities, Failed Auction, Value	319	363
Available-for-sale Securities, Fair Value Disclosure	319	363
Foreign Currency Contracts, Liability, Fair Value Disclosure	0	0
Derivative Financial Instruments, Liabilities, Fair Value Disclosure	0	0
Financial Instruments, Owned, at Fair Value	$ 319	$ 363