Fair Value Measurement (Details 2) (Contingent acquisition consideration, USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Contingent acquisition consideration
Reconciliation of the beginning and ending balances for the liabilities measured at fair value using significant unobservable inputs (Level 3)
Balance at the beginning of the period	$ (1,537)
Payment of contingent consideration	141
Change in fair value	(166)	308
Balance at the end of the period	$ (1,562)