INCOME TAXES - Income Tax Provision (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current:
Federal	$ 76,178	$ 69,102	$ 68,667
State	13,406	12,949	11,335
Foreign	7,158	14,464	7,534
Total current tax	96,742	96,515	87,536
Deferred:
Federal	17,249	(5,991)	1,286
State	1,610	2,892	2,078
Foreign	(223)	(149)	129
Total deferred tax	18,636	(3,248)	3,493
TOTAL PROVISION FOR INCOME TAXES	115,378	93,267	91,029
Reconciliation of primary factors causing income tax expense to be different than the federal statutory rate
Income tax at statutory rate	103,075	91,222	85,112
State income tax expense (net of federal benefit)	9,979	8,876	8,377
Foreign tax expense/(benefit)	(1,613)	9,857	(1,729)
Foreign tax	(221)	(19,155)	(2,816)
Repatriation tax under TCJA	7,956	0	0
Other	(3,798)	2,467	2,085
TOTAL PROVISION FOR INCOME TAXES	$ 115,378	$ 93,267	$ 91,029
Effective income tax rate	39.20%	35.80%	37.40%
Income taxes paid net of refunds	$ 90,702	$ 88,766	$ 82,690