Fair Value Measurement (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013 Level 3 Contingent acquisition consideration	Jun. 30, 2013 Level 3 Contingent acquisition consideration Minimum	Jun. 30, 2013 Level 3 Contingent acquisition consideration Maximum	Jun. 30, 2013 Recurring basis Total Fair Value	Dec. 31, 2012 Recurring basis Total Fair Value	Jun. 30, 2013 Recurring basis Total Fair Value Contingent acquisition consideration	Dec. 31, 2012 Recurring basis Total Fair Value Contingent acquisition consideration	Jun. 30, 2013 Recurring basis Level 2	Dec. 31, 2012 Recurring basis Level 2	Jun. 30, 2013 Recurring basis Level 3 Contingent acquisition consideration	Dec. 31, 2012 Recurring basis Level 3 Contingent acquisition consideration
Fair Value Inputs
Probability of contingent consideration (as a percent)		10.00%	95.00%
Weighted average discount rate (as a percent)	11.00%
Assets:
Interest Rate Swaps				$ 1,142				$ 1,142
Liabilities:
Interest Rate Swaps					(794)				(794)
Liabilities						$ (2,874)	$ (3,324)			$ (2,874)	$ (3,324)