INCOME TAXES (RateRec) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reconciliation between the effective income tax rate, as computed on income (loss) before income taxes, and the statutory federal income tax rate
Income tax provision at the statutory federal rate									$ 25,457	$ 24,714	$ 6,811
Federal income tax effects of:
State income taxes									(1,314)	(1,186)	(359)
Nondeductible expenses									1,426	1,239	1,090
Life insurance proceeds and changes in cash surrender value									(110)	(1,329)	(1,320)
Dividends received deduction									(3)	(6)	(9)
Alternative fuel tax credit									(1,141)	(1,148)	(1,935)
Increase (decrease) in valuation allowances									22	(696)	(1,436)
Other									(2,267)	(1,950)	(440)
Federal income tax provision									22,070	19,638	2,402
State income tax provision									3,754	3,389	1,026
Foreign income tax provision									2,056	1,408	222
Total provision (benefit) for income taxes	$ 1,878	$ 12,892	$ 12,942	$ 167	$ 5,097	$ 12,938	$ 10,163	$ (3,762)	$ 27,880	$ 24,435	$ 3,650
Effective tax rate (as a percent)									38.30%	34.60%	18.80%
Income taxes paid, excluding income tax refunds									$ 39,000	$ 40,400	$ 13,400
Income tax refunds									21,300	11,900	8,100
Tax benefit of options exercised and dividends on share-based payment awards										$ 100	$ 200
Maximum
Federal income tax effects of:
Tax benefit of options exercised and dividends on share-based payment awards									$ 100