INCOME TAXES - Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Activity related to unrecognized tax benefits
Unrecognized benefits, including interest and penalties	$ 20,000	$ 18,900	$ 16,500
Increase from prior period positions	1,400
Settlement of prior year positions	800
Decrease from lapse in statue of limitations	1,800
Gross unrecognized tax benefits at the beginning of the period	17,216	15,499	14,050
Increase in unrecognized tax benefits taken during a prior period	561		177
Increase in unrecognized tax benefits taken during the current period	2,321	1,717	1,498
Lapse in statute of limitations	(1,673)		(226)
Settlements	(521)
Gross unrecognized tax benefits at the end of the period	17,904	17,216	15,499
Interest and penalties accrued	2,100	$ 1,700	$ 1,000
Unrecognized tax benefits that would affect the effective tax rate if recognized	$ 20,000