LEASES (Details) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2019 USD ($) office
Leases [Abstract]
Number of buildings and offices under operating leases | office		106
Operating right-of-use lease assets	$ 54,515	$ 54,515
Operating lease liabilities	$ 57,638	$ 57,638
Weighted-average remaining lease term: Operating leases	5 years 9 months 18 days	5 years 9 months 18 days
Weighted-average discount rate: Operating leases	4.24%	4.24%
Operating lease cost	$ 3,858	$ 7,832
Short-term lease costs	99	222
Variable lease cost	567	1,128
Less sublease income	(231)	(468)
Total lease cost	4,293	8,714
Operating cash flows paid for operating lease amounts	3,800	7,700
Right-of-use assets in exchange for operating lease liabilities	2,900	64,100
Operating Lease Liabilities, Payments Due [Abstract]
Remainder of 2019	7,514	7,514
2020	14,330	14,330
2021	12,611	12,611
2022	9,083	9,083
2023	6,011	6,011
Thereafter	15,659	15,659
Total minimum lease payments	65,208	65,208
Less: amount of lease payments representing interest	(7,570)	(7,570)
Operating lease liabilities	$ 57,638	57,638
Undiscounted lease payments under an operating lease that had not yet commenced		$ 2,800
Lease not yet commenced, lease term	20 years	20 years