RETIREMENT ANNUITY AND GUARANTEED CONTINUOUS EMPLOYMENT PLANS (Pension Plan Assets by Level with the Fair Value Hierarchy) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Pension plans' assets by level within the fair value hierarchy
Total assets at fair value	$ 1,010,937		$ 939,995		$ 813,897
Quoted Prices in Active Markets for Identical Assets (Level 1)
Pension plans' assets by level within the fair value hierarchy
Total assets at fair value	32,178		0
Significant Other Observable Inputs (Level 2)
Pension plans' assets by level within the fair value hierarchy
Total assets at fair value	940,744		907,432
Significant Unobservable Inputs (Level 3)
Pension plans' assets by level within the fair value hierarchy
Total assets at fair value	38,015		32,563
Cash and cash equivalents
Pension plans' assets by level within the fair value hierarchy
Total assets at fair value	4,873
Cash and cash equivalents | Quoted Prices in Active Markets for Identical Assets (Level 1)
Pension plans' assets by level within the fair value hierarchy
Total assets at fair value	4,873
Cash and cash equivalents | Significant Other Observable Inputs (Level 2)
Pension plans' assets by level within the fair value hierarchy
Total assets at fair value	0
Cash and cash equivalents | Significant Unobservable Inputs (Level 3)
Pension plans' assets by level within the fair value hierarchy
Total assets at fair value	0
Corporate and other obligations
Pension plans' assets by level within the fair value hierarchy
Total assets at fair value	212,326	[1]
Corporate and other obligations | Quoted Prices in Active Markets for Identical Assets (Level 1)
Pension plans' assets by level within the fair value hierarchy
Total assets at fair value	0
Corporate and other obligations | Significant Other Observable Inputs (Level 2)
Pension plans' assets by level within the fair value hierarchy
Total assets at fair value	212,326
Corporate and other obligations | Significant Unobservable Inputs (Level 3)
Pension plans' assets by level within the fair value hierarchy
Total assets at fair value	0
Common Trusts and 103 by 12 Investments Cash and Cash Equivalents [Member]
Pension plans' assets by level within the fair value hierarchy
Total assets at fair value	7,499	[2]	4,686	[2]
Common Trusts and 103 by 12 Investments Cash and Cash Equivalents [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)
Pension plans' assets by level within the fair value hierarchy
Total assets at fair value	0		0
Common Trusts and 103 by 12 Investments Cash and Cash Equivalents [Member] | Significant Other Observable Inputs (Level 2)
Pension plans' assets by level within the fair value hierarchy
Total assets at fair value	7,499		4,686
Common Trusts and 103 by 12 Investments Cash and Cash Equivalents [Member] | Significant Unobservable Inputs (Level 3)
Pension plans' assets by level within the fair value hierarchy
Total assets at fair value	0		0
US Treasury Bond Securities [Member]
Pension plans' assets by level within the fair value hierarchy
Total assets at fair value	27,305	[1]
US Treasury Bond Securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1)
Pension plans' assets by level within the fair value hierarchy
Total assets at fair value	27,305
US Treasury Bond Securities [Member] | Significant Other Observable Inputs (Level 2)
Pension plans' assets by level within the fair value hierarchy
Total assets at fair value	0
US Treasury Bond Securities [Member] | Significant Unobservable Inputs (Level 3)
Pension plans' assets by level within the fair value hierarchy
Total assets at fair value	0
Common trusts and 103-12 investments
Pension plans' assets by level within the fair value hierarchy
Total assets at fair value	720,919	[2]	902,746	[2]
Common trusts and 103-12 investments | Quoted Prices in Active Markets for Identical Assets (Level 1)
Pension plans' assets by level within the fair value hierarchy
Total assets at fair value	0		0
Common trusts and 103-12 investments | Significant Other Observable Inputs (Level 2)
Pension plans' assets by level within the fair value hierarchy
Total assets at fair value	720,919		902,746
Common trusts and 103-12 investments | Significant Unobservable Inputs (Level 3)
Pension plans' assets by level within the fair value hierarchy
Total assets at fair value	0		0
Private equity funds
Pension plans' assets by level within the fair value hierarchy
Total assets at fair value	38,015	[3]	32,563	[3]
Private equity funds | Quoted Prices in Active Markets for Identical Assets (Level 1)
Pension plans' assets by level within the fair value hierarchy
Total assets at fair value	0		0
Private equity funds | Significant Other Observable Inputs (Level 2)
Pension plans' assets by level within the fair value hierarchy
Total assets at fair value	0		0
Private equity funds | Significant Unobservable Inputs (Level 3)
Pension plans' assets by level within the fair value hierarchy
Total assets at fair value	$ 38,015		$ 32,563

[1] Fixed income securities are primarily comprised of governmental and corporate bonds directly held by the plans. Governmental and corporate bonds are valued using both market observable inputs for similar assets that are traded on an active market and the closing price on the active market on which the individual securities are traded.

[2] Common trusts and 103-12 investments (collectively "Trusts") are comprised of a number of investment funds that invest in a diverse portfolio of assets including equity securities, corporate and governmental bonds, equity and credit indexes, and money markets. Trusts are valued at the net asset value ("NAV") as determined by their custodian. NAV represents the accumulation of the unadjusted quoted close prices on the reporting date for the underlying investments divided by the total shares outstanding at the reporting dates.

[3] Private equity funds consist of four funds seeking capital appreciation by investing in private equity investment partnerships and venture capital companies. Funds are comprised of unrestricted and restricted publicly traded securities and privately held securities. Unrestricted securities are valued at the closing market price on the reporting date. Restricted securities may be valued at a discount from such closing public market price, depending on facts and circumstances. Privately held securities are valued at fair value as determined by the fund directors and general partners.