FAIR VALUE MEASUREMENTS (Tables)

6 Months Ended

Jun. 30, 2018

Fair value of assets and liabilities measured on a recurring basis, categorized by level within the fair value hierarchy

The following tables summarize our financial assets and liabilities that were accounted for at fair value on a recurring basis, categorized by level within the fair value hierarchy:



	June 30, 2018
(in millions)	Level 1		Level 2		Level 3		Total
Derivative assets
Natural gas contracts	$	5.4	$	0.6	$	—	$	6.0
Petroleum products contracts	0.4		—		—		0.4
FTRs	—		—		16.7		16.7
Coal contracts	—		0.6		—		0.6
Total derivative assets	$	5.8	$	1.2	$	16.7	$	23.7

Investments held in rabbi trust	$	107.6	$	—	$	—	$	107.6

Derivative liabilities
Natural gas contracts	$	2.1	$	0.2	$	—	$	2.3
Coal contracts	—		0.3		—		0.3
Total derivative liabilities	$	2.1	$	0.5	$	—	$	2.6



	December 31, 2017
(in millions)	Level 1		Level 2		Level 3		Total
Derivative assets
Natural gas contracts	$	1.8	$	3.9	$	—	$	5.7
Petroleum products contracts	1.2		—		—		1.2
FTRs	—		—		4.4		4.4
Coal contracts	—		1.1		—		1.1
Total derivative assets	$	3.0	$	5.0	$	4.4	$	12.4

Investments held in rabbi trust	$	120.7	$	—	$	—	$	120.7

Derivative liabilities
Natural gas contracts	$	7.0	$	3.8	$	—	$	10.8
Coal contracts	—		0.8		—		0.8
Total derivative liabilities	$	7.0	$	4.6	$	—	$	11.6

Reconciliation of changes in fair value of items categorized as level 3 measurements

The following table summarizes the changes to derivatives classified as Level 3 in the fair value hierarchy:



	Three Months Ended June 30						Six Months Ended June 30
(in millions)	2018			2017			2018			2017
Balance at the beginning of the period	$	1.5		$	1.7		$	4.4		$	5.1
Purchases	18.4			13.8			18.4			13.8
Settlements	(3.2		)	(3.7		)	(6.1		)	(7.1		)
Balance at the end of the period	$	16.7		$	11.8		$	16.7		$	11.8

Schedule of carrying value and estimated fair value of financial instruments not recorded at fair value

The following table shows the financial instruments included on our balance sheets that are not recorded at fair value:



	June 30, 2018				December 31, 2017
(in millions)	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Preferred stock	$	30.4	$	28.7	$	30.4	$	30.5
Long-term debt, including current portion *	9,477.6		9,827.1		9,561.7		10,341.9


*	The carrying amount of long-term debt excludes capital lease obligations of $25.2 million and $27.0 million at June 30, 2018 and December 31, 2017, respectively.