BENEFIT PLANS, Asset Allocation and Fair Values of Pension Plan Assets (Details) - Pension Plan - USD ($) $ in Thousands	Dec. 31, 2015		Dec. 31, 2014
Pension Plan Assets [Abstract]
Weighted average asset allocation (in hundredths)	100.00%		100.00%
Fair value of plan assets	$ 302,147	[1]	$ 300,457	[2]
Level I
Pension Plan Assets [Abstract]
Fair value of plan assets	118,067	[1]	123,123	[2]
Level II
Pension Plan Assets [Abstract]
Fair value of plan assets	184,080	[1]	177,334	[2]
Level III
Pension Plan Assets [Abstract]
Fair value of plan assets	$ 0	[1]	$ 0	[2]
Mutual funds
Pension Plan Assets [Abstract]
Weighted average asset allocation (in hundredths)	39.00%		39.00%
Fair value of plan assets	$ 117,174		$ 119,543
Mutual funds | Level I
Pension Plan Assets [Abstract]
Fair value of plan assets	117,174		119,543
Mutual funds | Level II
Pension Plan Assets [Abstract]
Fair value of plan assets	0		0
Mutual funds | Level III
Pension Plan Assets [Abstract]
Fair value of plan assets	$ 0		$ 0
Fixed income securities
Pension Plan Assets [Abstract]
Weighted average asset allocation (in hundredths)	61.00%		58.00%
Cash equivalents and other
Pension Plan Assets [Abstract]
Weighted average asset allocation (in hundredths)	0.00%		3.00%
Foreign issued corporate debt
Pension Plan Assets [Abstract]
Fair value of plan assets	$ 12,825		$ 17,778
Foreign issued corporate debt | Level I
Pension Plan Assets [Abstract]
Fair value of plan assets	0		0
Foreign issued corporate debt | Level II
Pension Plan Assets [Abstract]
Fair value of plan assets	12,825		17,778
Foreign issued corporate debt | Level III
Pension Plan Assets [Abstract]
Fair value of plan assets	0		0
U.S. corporate debt
Pension Plan Assets [Abstract]
Fair value of plan assets	54,005		50,155
U.S. corporate debt | Level I
Pension Plan Assets [Abstract]
Fair value of plan assets	0		0
U.S. corporate debt | Level II
Pension Plan Assets [Abstract]
Fair value of plan assets	54,005		50,155
U.S. corporate debt | Level III
Pension Plan Assets [Abstract]
Fair value of plan assets	0		0
Government debt
Pension Plan Assets [Abstract]
Fair value of plan assets	8,273		10,239
Government debt | Level I
Pension Plan Assets [Abstract]
Fair value of plan assets	0		0
Government debt | Level II
Pension Plan Assets [Abstract]
Fair value of plan assets	8,273		10,239
Government debt | Level III
Pension Plan Assets [Abstract]
Fair value of plan assets	0		0
U.S. Treasury securities
Pension Plan Assets [Abstract]
Fair value of plan assets	90,414		81,552
U.S. Treasury securities | Level I
Pension Plan Assets [Abstract]
Fair value of plan assets	0		0
U.S. Treasury securities | Level II
Pension Plan Assets [Abstract]
Fair value of plan assets	90,414		81,552
U.S. Treasury securities | Level III
Pension Plan Assets [Abstract]
Fair value of plan assets	0		0
Asset-backed securities
Pension Plan Assets [Abstract]
Fair value of plan assets	18,563		17,610
Asset-backed securities | Level I
Pension Plan Assets [Abstract]
Fair value of plan assets	0		0
Asset-backed securities | Level II
Pension Plan Assets [Abstract]
Fair value of plan assets	18,563		17,610
Asset-backed securities | Level III
Pension Plan Assets [Abstract]
Fair value of plan assets	0		0
Cash Equivalents
Pension Plan Assets [Abstract]
Fair value of plan assets	893	[3]	3,580	[4]
Cash Equivalents | Level I
Pension Plan Assets [Abstract]
Fair value of plan assets	893	[3]	3,580	[4]
Cash Equivalents | Level II
Pension Plan Assets [Abstract]
Fair value of plan assets	0	[3]	0	[4]
Cash Equivalents | Level III
Pension Plan Assets [Abstract]
Fair value of plan assets	$ 0	[3]	$ 0	[4]

[1] Excludes cash and net payables relating to the purchase of securities that were not settled as of December 31, 2015.

[2] Excludes cash and net receivables relating to the sale of securities that were not settled as of December 31, 2014.

[3] Represents an investment in a money market fund.

[4] Represents an investment in a money market fund.