Commitments And Contingencies (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Commitments And Contingencies [Abstract]
Rental expense for operating leases	$ 7,365	$ 6,615	$ 6,428
Capitalized cost related to Company's co-location facility	26,000
Expected total capital expenditure	12,000
Defined benefit plan employer matching contribution on first five percent of employee compensation	50.00%
Percentage of employees' eligible compensation for employer matching contribution	5.00%
Defined benefit plan employer contribution limit	6
Defined benefit plan employer contribution vesting period	5 years
Defined benefit plan employer contribution	682
Compensation	$ 682	$ 545	$ 436