Fair value measurements (Tables)

3 Months Ended

Mar. 31, 2013

Fair Value Disclosures [Abstract]

Available-for-sale securities

Details of available-for-sale securities were as follows:

March 31, 2013	Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(In thousands)
Insurance contract	$	37,270	$	16,064	$	—		$	53,334
Mortgage-backed securities	8,749		133		(3		)	8,879
U.S. Treasury securities	1,301		39		—			1,340
Total	$	47,320	$	16,236	$	(3	)	$	63,553

March 31, 2012	Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(In thousands)
Insurance contract	$	37,250	$	11,454	$	—		$	48,704
Auction rate securities	11,400		—		—			11,400
Mortgage-backed securities	7,952		119		(1		)	8,070
U.S. Treasury securities	1,968		49		(1		)	2,016
Total	$	58,570	$	11,622	$	(2	)	$	70,190

December 31, 2012	Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(In thousands)
Insurance contract	$	37,250	$	11,648	$	—		$	48,898
Mortgage-backed securities	8,054		144		(3		)	8,195
U.S. Treasury securities	1,763		43		—			1,806
Total	$	47,067	$	11,835	$	(3	)	$	58,899

Assets and liabilities measured at fair value on a recurring basis

The Company's assets and liabilities measured at fair value on a recurring basis are as follows:

	Fair Value Measurements at March 31, 2013, Using
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Balance at March 31, 2013
	(In thousands)
Assets:
Money market funds	$	—	$	31,281	$	—	$	31,281
Available-for-sale securities:
Insurance contract*	—		53,334		—		53,334
Mortgage-backed securities	—		8,879		—		8,879
U.S. Treasury securities	—		1,340		—		1,340
Commodity derivative instruments	—		6,179		—		6,179
Total assets measured at fair value	$	—	$	101,013	$	—	$	101,013
Liabilities:
Commodity derivative instruments	$	—	$	7,987	$	—	$	7,987
Interest rate derivative instruments	—		4,458		—		4,458
Total liabilities measured at fair value	$	—	$	12,445	$	—	$	12,445

*  The insurance contract invests approximately 29 percent in common stock of mid-cap companies, 28 percent in common stock of small-cap companies, 28 percent in common stock of large-cap companies and 15 percent in fixed-income and other investments.

	Fair Value Measurements at March 31, 2012, Using
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Balance at March 31, 2012
	(In thousands)
Assets:
Money market funds	$	—	$	9,942	$	—	$	9,942
Available-for-sale securities:
Insurance contract*	—		48,704		—		48,704
Auction rate securities	—		11,400		—		11,400
Mortgage-backed securities	—		8,070		—		8,070
U.S. Treasury securities	—		2,016		—		2,016
Commodity derivative instruments	—		27,280		—		27,280
Total assets measured at fair value	$	—	$	107,412	$	—	$	107,412
Liabilities:
Commodity derivative instruments	$	—	$	26,330	$	—	$	26,330
Interest rate derivative instruments	—		3,321		—		3,321
Total liabilities measured at fair value	$	—	$	29,651	$	—	$	29,651

*  The insurance contract invests approximately 29 percent in common stock of mid-cap companies, 29 percent in common stock of small-cap companies, 29 percent in common stock of large-cap companies and 13 percent in fixed-income and other investments.

	Fair Value Measurements at December 31, 2012, Using
	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs  (Level 3)		Balance at December 31, 2012
	(In thousands)
Assets:
Money market funds	$	—	$	24,240	$	—	$	24,240
Available-for-sale securities:
Insurance contract*	—		48,898		—		48,898
Mortgage-backed securities	—		8,195		—		8,195
U.S. Treasury securities	—		1,806		—		1,806
Commodity derivative instruments	—		18,304		—		18,304
Total assets measured at fair value	$	—	$	101,443	$	—	$	101,443
Liabilities:
Interest rate derivative instruments	$	—	$	6,255	$	—	$	6,255
Total liabilities measured at fair value	$	—	$	6,255	$	—	$	6,255

* The insurance contract invests approximately 28 percent in common stock of mid-cap companies, 28 percent in common stock of small-cap companies, 29 percent in common stock of large-cap companies and 15 percent in fixed-income and other investments.

Fair value of long term debt outstanding

The estimated fair value of the Company's Level 2 long-term debt was as follows:

	Carrying Amount		Fair Value
	(In thousands)
Long-term debt at March 31, 2013	$	1,789,663	$	1,925,859
Long-term debt at March 31, 2012	$	1,416,189	$	1,578,395
Long-term debt at December 31, 2012	$	1,744,975	$	1,888,135