SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES INVENTORIES (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Percentage of total inventories stated on a LIFO basis	37.00%us-gaap_PercentageOfLIFOInventory	30.00%us-gaap_PercentageOfLIFOInventory
PGL and NSG
Amount by which estimated replacement cost of natural gas in inventory exceeded LIFO cost	$ 47.7	$ 151.7
Natural Gas Price Benchmark	3.04	4.77

The excess of replacement or current cost over the stated LIFO (last in first out) inventory value when the LIFO inventory method is utilized.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.6(c))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 6

-Subparagraph c

-Article 5

Name:	us-gaap_ExcessOfReplacementOrCurrentCostsOverStatedLIFOValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant