GEOGRAPHIC AREAS - Long-Lived Assets by Geographic Area (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 9,324	$ 9,438	$ 6,923
U.S.
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	8,069	8,116	5,523
Canada
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	579	652	728
Other foreign countries
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 676	$ 670	$ 672