Line Of Credit (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2012
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	$ 50.0
Line of credit facility, commitment increase	25.0
Line of credit facility, allowable issuance amount of letters of credit	1.0
Credit agreement, final maturity date	May 23, 2015
Line of credit, interest rate at period end	0.214%
Line of credit facility, available borrowing capacity	$ 38.5
Line of credit facility, percentage of annual commitment fee on unused capacity	0.30%
Minimum [Member]
Line of Credit Facility [Line Items]
Line of credit, margin interest rate percentage	2.50%
Ratio of EBITDA plus stock compensation and minus income taxes paid and capital expenditures to interest expense and scheduled payments due for borrowings	1.00
Ratio of current maturities of long-term debt to EBITDA plus stock compensation and minus income taxes paid and capital expenditures	1.00
Maximum [Member]
Line of Credit Facility [Line Items]
Line of credit, margin interest rate percentage	3.00%
Ratio of EBITDA plus stock compensation and minus income taxes paid and capital expenditures to interest expense and scheduled payments due for borrowings	2.00
Ratio of current maturities of long-term debt to EBITDA plus stock compensation and minus income taxes paid and capital expenditures	2.75
Silicon Valley Bank Lender [Member]
Line of Credit Facility [Line Items]
Line of credit, interest rate at period end	4.00%
Silicon Valley Bank Lender [Member] | Minimum [Member]
Line of Credit Facility [Line Items]
Line of credit, margin interest rate percentage	0.00%
Silicon Valley Bank Lender [Member] | Maximum [Member]
Line of Credit Facility [Line Items]
Line of credit, margin interest rate percentage	0.50%