Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2016

Summary Of Assets And Liabilities Accounted At Fair Value On A Recurring Basis

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



	June 30, 2016
	Level 1			Level 2			Total
Derivative instruments
Risk management assets—Commodity forward contracts	$	1,607		$	8,401		$	10,008
Risk management liabilities—Commodity forward contracts	(7,348		)	(373		)	(7,721		)
Marketable securities
Available-for-sale securities	109,337			352,021			461,358

	December 31, 2015
	Level 1			Level 2			Total
Derivative instruments
Risk management assets—Commodity forward contracts	$	5,553		$	—		$	5,553
Risk management liabilities—Commodity forward contracts	(11,648		)	(10,114		)	(21,762		)
Marketable securities
Available-for-sale securities	48,081			520,144			568,225

Summary Of Carrying And Fair Values Of Long-Term Debt

The carrying and fair values of the Company's long-term debt are summarized in the table below. The Company's long-term debt instruments are publicly-traded. A market approach, based upon quotes from financial reporting services, is used to measure the fair value of the Company's long-term debt. Because the Company's long-term debt instruments may not be actively traded, the inputs used to measure the fair value of the Company's long-term debt are classified as Level 2 inputs within the fair value hierarchy.



	June 30, 2016				December 31, 2015
	Carrying Value		Fair Value		Carrying Value		Fair Value
3.60% senior notes due 2022	$	247,939	$	251,523	$	247,768	$	244,828
6 ½% senior notes due 2029	99,048		120,125		99,011		117,153
6 ¾% senior notes due 2032	248,057		268,790		247,998		268,490
6 ½% GO Zone Senior Notes Due 2035	88,138		107,025		88,116		106,491
6 ½% IKE Zone Senior Notes Due 2035	64,382		78,127		64,366		76,741
Loan related to tax-exempt waste disposal revenue bonds due 2027	10,889		10,889		10,889		10,889