Fair value measurements (Tables)

6 Months Ended

Jun. 30, 2013

Fair Value Disclosures [Abstract]

Available-for-sale securities

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

June 30, 2013	Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(In thousands)
Insurance contract	$	37,270	$	16,769	$	—		$	54,039
Mortgage-backed securities	8,035		58		(41		)	8,052
U.S. Treasury securities	1,920		15		(15		)	1,920
Total	$	47,225	$	16,842	$	(56	)	$	64,011

June 30, 2012	Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(In thousands)
Insurance contract	$	37,250	$	8,709	$	—		$	45,959
Mortgage-backed securities	8,130		128		(5		)	8,253
U.S. Treasury securities	1,958		37		(1		)	1,994
Total	$	47,338	$	8,874	$	(6	)	$	56,206

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 June 30, 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 June 30, 2013
	(In thousands)
Assets:
Money market funds	$	—	$	29,902	$	—	$	29,902
Available-for-sale securities:
Insurance contract*	—		54,039		—		54,039
Mortgage-backed securities	—		8,052		—		8,052
U.S. Treasury securities	—		1,920		—		1,920
Commodity derivative instruments	—		11,244		—		11,244
Total assets measured at fair value	$	—	$	105,157	$	—	$	105,157
Liabilities:
Commodity derivative instruments	$	—	$	1,388	$	—	$	1,388
Total liabilities measured at fair value	$	—	$	1,388	$	—	$	1,388

*  The insurance contract invests approximately 28 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 16 percent in fixed-income and other investments.

	Fair Value Measurements at June 30, 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 June 30, 2012
	(In thousands)
Assets:
Money market funds	$	—	$	21,054	$	—	$	21,054
Available-for-sale securities:
Insurance contract*	—		45,959		—		45,959
Mortgage-backed securities	—		8,253		—		8,253
U.S. Treasury securities	—		1,994		—		1,994
Commodity derivative instruments	—		48,657		—		48,657
Total assets measured at fair value	$	—	$	125,917	$	—	$	125,917
Liabilities:
Commodity derivative instruments	$	—	$	1,037	$	—	$	1,037
Interest rate derivative instruments	—		6,963		—		6,963
Total liabilities measured at fair value	$	—	$	8,000	$	—	$	8,000

*  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 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 June 30, 2013	$	2,006,754	$	2,090,208
Long-term debt at June 30, 2012	$	1,665,631	$	1,839,430
Long-term debt at December 31, 2012	$	1,744,975	$	1,888,135