Commitments and Contingencies (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			6 Months Ended
	Jun. 30, 2013	Mar. 31, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Commitments and Contingencies [Line Items]
Rental expense for operating leases	$ 2,284	$ 2,284	$ 1,746	$ 4,785	$ 3,345
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 [Member]
Commitments and Contingencies [Line Items]
Percentage of employees' eligible compensation for employer matching contribution				5.00%
Salaries And Related Expenses [Member]
Commitments and Contingencies [Line Items]
Defined benefit plan employer contribution	$ 245		$ 197	$ 471	$ 364