ACCOUNTS PAYABLE AND ACCRUED LIABILITIES (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
ACCOUNTS PAYABLE AND ACCRUED LIABILITIES.
Accounts payable, principally trade	$ 153,862	$ 115,514
Accrued employee compensation costs	144,175	119,767
Customer deposits and other unearned income	45,196	44,068
Other accrued liabilities	118,346	89,790
Total	$ 461,579	$ 369,139