INCOME TAXES - Unrecognized tax benefits (Details)	12 Months Ended
	Dec. 31, 2016 USD ($) item	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Reconciliation of the change in the amount of unrecognized tax benefits
Balance at beginning of period	$ 30,100,000	$ 30,500,000	$ 27,400,000
Gross increases-current period tax positions	1,700,000	1,700,000	1,600,000
Gross increases-prior periods tax position	100,000	1,100,000	1,500,000
Favorable resolutions with authorities	(19,200,000)	(2,200,000)
Lapse of statute of limitations		(1,000,000)
Balance at end of period	12,700,000	30,100,000	$ 30,500,000
Gross decreases-tax position in prior periods		800,000
Interest expense recognized	5,000	1,000,000
Unrecognized tax benefits that would impact the effective tax rate	$ 9,327,000	27,276,000
Number of subsidiaries files income tax returns in the U.S. federal jurisdiction, and various state and foreign jurisdictions | item	1
State
Reconciliation of the change in the amount of unrecognized tax benefits
Interest expense recognized	$ 15,000
Accrued interest and penalties	$ 81,000	$ 69,000