COMMITMENTS AND CONTINGENCIES - Lease Commitments (Details) $ in Thousands, ft² in Millions	12 Months Ended
	Dec. 31, 2015 USD ($) ft²	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
COMMITMENTS AND CONTINGENCIES
Area of lease (in square feet) | ft²	2.6
Obligation for payments under leases
2016	$ 25,046
2017	21,919
2018	16,754
2019	10,080
2020	6,999
Thereafter	13,560
Total obligations under operating leases	94,358
Rent expense
Rent expense	$ 17,000	$ 15,000	$ 12,700