Accounts Payable and Accrued Expenses (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Payables and Accruals [Line Items]
Trade accounts payable	$ 11,815	$ 11,061
Accrued salaries, vacation and benefits	15,731	16,463
Other accrued expenses	20,127	17,393
Accrued contingent consideration	2,405	2,540
Negative cash book balance	5,261	0
Accounts Payable and Accrued Liabilities, Current, Total	$ 55,339	$ 47,457