STOCK-BASED COMPENSATION – STOCK OPTIONS, PERFORMANCE STOCK RIGHTS, AND RESTRICTED SHARE UNIT ACTIVITY (Details) - 6 months ended Jun. 30, 2015 - USD ($) $ in Millions	Total
Stock options
Stock Options
Outstanding, at the beginning of the period (in shares)	134,017
Granted (in shares)	0
Exercised (in shares)	(70,692)
Forfeited (in shares)	0
Canceled due to WEC Merger (in shares)	(63,325)
Outstanding, at the end of the period (in shares)	0
Performance stock rights
Performance Stock Rights and Restricted Share Unit Awards
Outstanding at the beginning of the period (in shares)	238,571
Granted (in shares)	0
Distributed (in shares)	(40,385)
Adjustment for performance stock rights distributed or canceled (in shares)	169,379
Forfeited (in shares)	0
Canceled due to WEC Merger (in shares)	(367,565)
Outstanding at the end of period (in shares)	0
Additional disclosures
Intrinsic value of awards canceled due to WEC merger	$ 26.0
Tax benefit realized from the payment of canceled awards	10.0
Intrinsic value of shares distributed for performance stock rights	$ 3.1
Restricted share units
Performance Stock Rights and Restricted Share Unit Awards
Outstanding at the beginning of the period (in shares)	427,305
Granted (in shares)	224,784
Dividend equivalents (in shares)	9,154
Vested and released (in shares)	(166,681)
Forfeited (in shares)	(948)
Canceled due to WEC Merger (in shares)	(493,614)
Outstanding at the end of period (in shares)	0
Additional disclosures
Intrinsic value of awards canceled due to WEC merger	$ 34.8
Tax benefit realized from the payment of canceled awards	12.3
Intrinsic value of restricted share units vested and released	12.8
Tax benefit realized from the vesting and release of restricted share units	$ 5.1