Income Taxes (Narrative) (Details) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2011	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Income Tax Contingency [Line Items]
Deferred tax assets		$ 9,171,000	$ 125,000
Valuation allowance		4,198,000	32,637,000
Reduction in valuation allowance	24,500,000	28,400,000
Effect of excess tax deductions from stock options on deferred tax assets and valuation allowance		6,900,000
U.S. federal net operating loss carryforwards		29,200,000	6,300,000
Foreign tax credit carryforwards		1,900,000
Undistributed foreign earnings		11,500,000
Accrued interest and penalties related to tax positions		100,000	100,000
Liability for uncertain tax positions		800,000	1,000,000	800,000	500,000
Allowance Against State Net Operating Losses [Member]
Income Tax Contingency [Line Items]
Valuation allowance		1,200,000	1,100,000
Allowance Against Impairment Loss For Auction Rate Securities [Member]
Income Tax Contingency [Line Items]
Valuation allowance		1,100,000	1,200,000
Allowance Against Foreign Tax Credits [Member]
Income Tax Contingency [Line Items]
Valuation allowance		1,900,000
Foreign tax credit carryforwards			1,900,000
U.S. Deferred Tax Assets, Excluding Deferred Tax Liabilities Related To Indefinite-Lived Assets [Member]
Income Tax Contingency [Line Items]
Valuation allowance			28,400,000
Subject To Limitation [Member]
Income Tax Contingency [Line Items]
U.S. federal net operating loss carryforwards		$ 23,500,000
Federal [Member]
Income Tax Contingency [Line Items]
Beginning expiration year for federal net operating loss carryforwards		2022
Final expiration year for state net operating losses		2022
State [Member]
Income Tax Contingency [Line Items]
Beginning expiration year for federal net operating loss carryforwards		2031
Final expiration year for state net operating losses		2031