DEBT (Details) - USD ($) $ in Thousands		1 Months Ended	6 Months Ended
	Apr. 01, 2015	Oct. 31, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2013	Jul. 20, 2012
Line of credit | GE
Debt
Maximum borrowing capacity	$ 175,000			$ 120,000	$ 85,000	$ 60,000
Letters of credit | GE
Debt
Maximum borrowing capacity				10,000
Deferred draw term loan | GE
Debt
Maximum borrowing capacity	25,000
Deferred financing costs	5,131
Term Loan A | GE
Debt
Maximum borrowing capacity	$ 120,000
Swing loans | GE
Debt
Maximum borrowing capacity				$ 15,000
Minimum | Line of credit
Debt
Monthly unused commitment fee (as a percent)			0.25%
Maximum | Line of credit
Debt
Monthly unused commitment fee (as a percent)			0.50%
Initial Public Offering
Debt
Existing indebtedness to certain current or former shareholders and employees		$ 19,824
Amount of borrowings repaid under the revolving line of credit		$ 60,634
Base Rate | Line of credit | GE
Debt
Variable rate basis			Base Rate
Interest rate margin (as a percent)			1.75%
LIBOR | Line of credit | GE
Debt
Variable rate basis			LIBOR
Interest rate margin (as a percent)			0.25%