Income Taxes (Details 4) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Tax credit carryforwards
Interest and penalty expense recognized related to unrecognized tax benefits	$ 200,000	$ 200,000	$ 200,000
Reconciliation of the beginning and ending balance of unrecognized tax benefits
Balance at beginning of year	7,645,000	7,719,000
Increases in unrecognized tax benefits as a result of tax positions taken during a prior period	92,000	324,000
Increases in unrecognized tax benefits as a result of tax positions taken during the current period	223,000
Reductions to unrecognized tax benefits as a result of a lapse of the applicable statute of limitations		(398,000)
Balance at end of year	7,960,000	7,645,000	7,719,000
Recorded as other long-term liability	2,328,000	2,343,000
Recorded as a decrease in deferred tax assets and offsetting valuation allowance	5,632,000	5,302,000
Unrecognized tax benefits	7,960,000	7,645,000	7,719,000
Research and development and other tax credit carryforwards
Tax credit carryforwards
Tax credit carryforwards	18,100,000
Foreign
Tax credit carryforwards
Tax credit carryforwards	$ 3,900,000