Employee Benefit Plan (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Employee Benefit Plan [Abstract]
Maximum annual contribution per employee, percent	60.00%
Percentage of participant's contributions matched by employer	60.00%
Employer matching contribution, percent	8.00%
Employer contributions	$ 378	$ 321	$ 297