EMPLOYEE BENEFIT PLANS - PILOT LONG-TERM DISABILITY BENEFITS (Details) - Postretirement Health Coverage [Member] - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Total liability net of a prefunded trust account	$ 19	$ 16
Prefunded trust account	$ 2	$ 2

Aggregate carrying value as of the balance sheet date of the liabilities for deferred compensation arrangements payable after one year (or the operating cycle, if longer) other than those specified elsewhere in the taxonomy.

No definition available.

Name:	us-gaap_OtherDeferredCompensationArrangementsLiabilityClassifiedNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant