Fair Value Measurements (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Rollforward of contingent consideration liability level three fair value measurements
Change in fair value of contingent consideration	$ (4,955)	$ (4,886)
Contingent Consideration Liability
Rollforward of contingent consideration liability level three fair value measurements
Balance at the beginning of the period	6,922	9,233
Change in fair value of contingent consideration	45	114
Balance at the end of the period	1,967	4,347
Additional information
Number of unobservable inputs	2
Minimum probability of acquired entity meeting contractual operating performance target (as a percent)	33.00%
Maximum probability of acquired entity meeting contractual operating performance target (as a percent)	100.00%
Contingent Consideration Liability | Q3 Contracting
Rollforward of contingent consideration liability level three fair value measurements
Payments	$ (5,000)	$ (5,000)