Commitments And Contingencies (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Commitments and Contingencies [Line Items]
Rental expense for operating leases	$ 2,501	$ 1,599
Defined benefit plan employer matching contribution on first five percent of employee compensation	50.00%
Defined benefit plan employer contribution limit	6
Defined benefit plan employer contribution vesting period	5 years
Maximum
Commitments and Contingencies [Line Items]
Percentage of employees' eligible compensation for employer matching contribution	5.00%
Salaries And Related Expenses
Commitments and Contingencies [Line Items]
Defined benefit plan employer contribution	$ 226	$ 167