EMPLOYEE BENEFIT PLANS (Details 3) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Estimated Fair Value
Fair Value Measurements
Total	$ 755.0	$ 817.0
Fair Value Measurements for Level 1, 2 and 3 assets
Balance at the end of the period	755.0	817.0
Estimated Fair Value | Common stock
Fair Value Measurements
Total	324.0	363.0
Fair Value Measurements for Level 1, 2 and 3 assets
Balance at the end of the period	324.0	363.0
Estimated Fair Value | Preferred stock
Fair Value Measurements
Total	1.0
Fair Value Measurements for Level 1, 2 and 3 assets
Balance at the end of the period	1.0
Estimated Fair Value | Mutual funds
Fair Value Measurements
Total	183.0	206.0
Fair Value Measurements for Level 1, 2 and 3 assets
Balance at the end of the period	183.0	206.0
Estimated Fair Value | Short-term investment vehicles
Fair Value Measurements
Total	23.0	18.0
Fair Value Measurements for Level 1, 2 and 3 assets
Balance at the end of the period	23.0	18.0
Estimated Fair Value | Government agency securities
Fair Value Measurements
Total	32.0	51.0
Fair Value Measurements for Level 1, 2 and 3 assets
Balance at the end of the period	32.0	51.0
Estimated Fair Value | Corporate debt securities
Fair Value Measurements
Total	51.0	51.0
Fair Value Measurements for Level 1, 2 and 3 assets
Balance at the end of the period	51.0	51.0
Estimated Fair Value | Loans secured by mortgages
Fair Value Measurements
Total	12.0	9.0
Fair Value Measurements for Level 1, 2 and 3 assets
Balance at the end of the period	12.0	9.0
Estimated Fair Value | Municipals
Fair Value Measurements
Total	4.0	3.0
Fair Value Measurements for Level 1, 2 and 3 assets
Balance at the end of the period	4.0	3.0
Estimated Fair Value | Common collective trusts
Fair Value Measurements
Total	37.0	45.0
Fair Value Measurements for Level 1, 2 and 3 assets
Balance at the end of the period	37.0	45.0
Estimated Fair Value | Limited partnerships
Fair Value Measurements
Total	23.0	26.0
Fair Value Measurements for Level 1, 2 and 3 assets
Balance at the end of the period	23.0	26.0
Estimated Fair Value | Multi-strategy hedge funds
Fair Value Measurements
Total	65.0	45.0
Fair Value Measurements for Level 1, 2 and 3 assets
Balance at the end of the period	65.0	45.0
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value Measurements
Total	345.0	389.0
Fair Value Measurements for Level 1, 2 and 3 assets
Balance at the end of the period	345.0	389.0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Common stock
Fair Value Measurements
Total	324.0	363.0
Fair Value Measurements for Level 1, 2 and 3 assets
Balance at the end of the period	324.0	363.0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Preferred stock
Fair Value Measurements
Total	1.0
Fair Value Measurements for Level 1, 2 and 3 assets
Balance at the end of the period	1.0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Mutual funds
Fair Value Measurements
Total	20.0	25.0
Fair Value Measurements for Level 1, 2 and 3 assets
Balance at the end of the period	20.0	25.0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Limited partnerships
Fair Value Measurements
Total		1.0
Fair Value Measurements for Level 1, 2 and 3 assets
Balance at the end of the period		1.0
Significant Other Observable Inputs (Level 2)
Fair Value Measurements
Total	345.0	383.0
Fair Value Measurements for Level 1, 2 and 3 assets
Balance at the end of the period	345.0	383.0
Significant Other Observable Inputs (Level 2) | Mutual funds
Fair Value Measurements
Total	163.0	181.0
Fair Value Measurements for Level 1, 2 and 3 assets
Balance at the end of the period	163.0	181.0
Significant Other Observable Inputs (Level 2) | Short-term investment vehicles
Fair Value Measurements
Total	23.0	18.0
Fair Value Measurements for Level 1, 2 and 3 assets
Balance at the end of the period	23.0	18.0
Significant Other Observable Inputs (Level 2) | Government agency securities
Fair Value Measurements
Total	32.0	51.0
Fair Value Measurements for Level 1, 2 and 3 assets
Balance at the end of the period	32.0	51.0
Significant Other Observable Inputs (Level 2) | Corporate debt securities
Fair Value Measurements
Total	51.0	51.0
Fair Value Measurements for Level 1, 2 and 3 assets
Balance at the end of the period	51.0	51.0
Significant Other Observable Inputs (Level 2) | Loans secured by mortgages
Fair Value Measurements
Total	12.0	9.0
Fair Value Measurements for Level 1, 2 and 3 assets
Balance at the end of the period	12.0	9.0
Significant Other Observable Inputs (Level 2) | Municipals
Fair Value Measurements
Total	4.0	3.0
Fair Value Measurements for Level 1, 2 and 3 assets
Balance at the end of the period	4.0	3.0
Significant Other Observable Inputs (Level 2) | Common collective trusts
Fair Value Measurements
Total	37.0	45.0
Fair Value Measurements for Level 1, 2 and 3 assets
Balance at the end of the period	37.0	45.0
Significant Other Observable Inputs (Level 2) | Limited partnerships
Fair Value Measurements
Total	23.0	25.0
Fair Value Measurements for Level 1, 2 and 3 assets
Balance at the end of the period	23.0	25.0
Significant Other Unobservable Inputs (Level 3)
Fair Value Measurements
Total	65.0	45.0
Fair Value Measurements for Level 1, 2 and 3 assets
Balance at the beginning of the period	45.0	14.0
Unrealized gains or (losses) included in changes in net assets	(1)	2
Purchases, issuances, and settlements	21	29
Balance at the end of the period	65.0	45.0
Significant Other Unobservable Inputs (Level 3) | Multi-strategy hedge funds
Fair Value Measurements
Total	65.0	45.0
Fair Value Measurements for Level 1, 2 and 3 assets
Balance at the end of the period	$ 65.0	$ 45.0