Supplemental Guarantor/Non-Guarantor Financial Information (Details 2) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Supplemental Condensed Consolidating Statement of Operations and Comprehensive Income
Revenue	$ 244,148	$ 320,850	$ 561,701	$ 639,916
Costs and expenses
Cost of product sold (exclusive of depreciation, depletion, amortization, and accretion, shown separately)	222,443	270,121	486,760	542,060
Depreciation and depletion	19,310	29,200	43,846	56,128
Amortization of port access contract rights	928	0	1,855	0
Accretion	3,348	4,088	6,890	8,217
Derivative financial instruments	2,761	(2,803)	7,546	(15,537)
Selling, general and administrative expenses	12,511	12,483	23,760	24,924
Goodwill impairment	33,355	0	33,355	0
Other operating costs	304	333	517	573
Total costs and expenses	294,960	313,422	604,529	616,365
Operating income (loss)	(50,812)	7,428	(42,828)	23,551
Other income (expense)
Interest income	50	61	99	185
Interest expense	(12,621)	(13,813)	(25,289)	(51,807)
Other, net	244	233	(93)	(231)
Total other income (expense)	(12,327)	(13,519)	(25,283)	(51,853)
Income (loss) before income tax provision and earnings from unconsolidated affiliates	(63,139)	(6,091)	(68,111)	(28,302)
Income tax benefit (expense)	9,866	3,489	10,146	9,979
Earnings from unconsolidated affiliates, net of tax	376	454	388	549
Net income (loss)	(52,897)	(2,148)	(57,577)	(17,774)
Other comprehensive income (loss)
Postretirement medical plan amortization of prior service cost	313	247	626	494
Income tax on postretirement medical plan	(116)	(89)	(232)	(178)
Other comprehensive income (loss)	197	158	394	316
Total comprehensive income (loss)	(52,700)	(1,990)	(57,183)	(17,458)
Eliminations
Supplemental Condensed Consolidating Statement of Operations and Comprehensive Income
Revenue	(2,156)	(1,975)	(4,275)	(3,875)
Costs and expenses
Cost of product sold (exclusive of depreciation, depletion, amortization, and accretion, shown separately)	0	0
Depreciation and depletion	0	0
Amortization of port access contract rights	0	0
Accretion	0	0
Derivative financial instruments	0	0
Selling, general and administrative expenses	(2,156)	(1,975)	(4,275)	(3,875)
Other operating costs	0	0
Total costs and expenses	(2,156)	(1,975)	(4,275)	(3,875)
Operating income (loss)	0	0
Other income (expense)
Interest income	0	0
Interest expense	0	0
Total other income (expense)	0	0
Income (loss) before income tax provision and earnings from unconsolidated affiliates	0	0
Income tax benefit (expense)	0	0
Earnings (losses) from consolidated affiliates, net of tax	96,907	(2,521)	94,860	2,387
Net income (loss)	96,907	(2,521)	94,860	2,387
Other comprehensive income (loss)
Postretirement medical plan amortization of prior service cost	(626)	(494)	(1,252)	(988)
Income tax on postretirement medical plan	232	178	464	356
Other comprehensive income (loss)	(394)	(316)	(788)	(632)
Total comprehensive income (loss)	96,513	(2,837)	94,072	1,755
Parent Guarantor (CPE Inc.)
Supplemental Condensed Consolidating Statement of Operations and Comprehensive Income
Revenue	2,156	1,975	4,275	3,875
Costs and expenses
Cost of product sold (exclusive of depreciation, depletion, amortization, and accretion, shown separately)	0	0	0	0
Depreciation and depletion	0	0	0	0
Amortization of port access contract rights	0	0	0	0
Accretion	0	0	0	0
Derivative financial instruments	0	0	0	0
Selling, general and administrative expenses	2,165	1,975	4,284	3,875
Goodwill impairment	0		0	0
Other operating costs	0	0	0	0
Total costs and expenses	2,165	1,975	4,284	3,875
Operating income (loss)	(9)	0	(9)	0
Other income (expense)
Interest income	0	0	0	0
Interest expense	0	0	0	0
Other, net	0	0	0	0
Total other income (expense)	0	0	0	0
Income (loss) before income tax provision and earnings from unconsolidated affiliates	(9)	0	(9)	0
Income tax benefit (expense)	1	0	1	0
Earnings from unconsolidated affiliates, net of tax	0	0	0	0
Earnings (losses) from consolidated affiliates, net of tax	(52,889)	(2,148)	(57,569)	(17,774)
Net income (loss)	(52,897)	(2,148)	(57,577)	(17,774)
Other comprehensive income (loss)
Postretirement medical plan amortization of prior service cost	313	247	626	494
Income tax on postretirement medical plan	(116)	(89)	(232)	(178)
Other comprehensive income (loss)	197	158	394	316
Total comprehensive income (loss)	(52,700)	(1,990)	(57,183)	(17,458)
Issuers
Supplemental Condensed Consolidating Statement of Operations and Comprehensive Income
Revenue	0	0	0	0
Costs and expenses
Cost of product sold (exclusive of depreciation, depletion, amortization, and accretion, shown separately)	10	28	18	197
Depreciation and depletion	645	778	1,292	1,535
Amortization of port access contract rights	0	0	0	0
Accretion	0	0	0	0
Derivative financial instruments	0	0	0	0
Selling, general and administrative expenses	167	162	454	360
Goodwill impairment	0		0	0
Other operating costs	0	0	0	45
Total costs and expenses	822	968	1,764	2,137
Operating income (loss)	(822)	(968)	(1,764)	(2,137)
Other income (expense)
Interest income	50	61	99	185
Interest expense	(10,967)	(10,938)	(22,070)	(46,054)
Other, net	(44)	(116)	(131)	(781)
Total other income (expense)	(10,961)	(10,993)	(22,102)	(46,650)
Income (loss) before income tax provision and earnings from unconsolidated affiliates	(11,783)	(11,961)	(23,866)	(48,787)
Income tax benefit (expense)	2,876	3,653	3,555	12,784
Earnings from unconsolidated affiliates, net of tax	0	0	(1)	(16)
Earnings (losses) from consolidated affiliates, net of tax	(43,982)	6,160	(37,257)	18,245
Net income (loss)	(52,889)	(2,148)	(57,569)	(17,774)
Other comprehensive income (loss)
Postretirement medical plan amortization of prior service cost	313	247	626	494
Income tax on postretirement medical plan	(116)	(89)	(232)	(178)
Other comprehensive income (loss)	197	158	394	316
Total comprehensive income (loss)	(52,692)	(1,990)	(57,175)	(17,458)
Guarantor Subsidiaries
Supplemental Condensed Consolidating Statement of Operations and Comprehensive Income
Revenue	244,148	315,258	561,701	630,359
Costs and expenses
Cost of product sold (exclusive of depreciation, depletion, amortization, and accretion, shown separately)	222,433	263,358	486,742	529,954
Depreciation and depletion	18,665	28,444	42,554	54,833
Amortization of port access contract rights	928	0	1,855	0
Accretion	3,348	3,072	6,890	6,186
Derivative financial instruments	2,761	(2,803)	7,546	(15,537)
Selling, general and administrative expenses	12,335	12,321	23,296	24,564
Goodwill impairment	33,355		33,355	0
Other operating costs	304	333	517	527
Total costs and expenses	294,129	304,725	602,755	600,527
Operating income (loss)	(49,981)	10,533	(41,054)	29,832
Other income (expense)
Interest income	0	0	0	0
Interest expense	(1,568)	(2,775)	(3,049)	(5,554)
Other, net	244	233	(93)	346
Total other income (expense)	(1,324)	(2,542)	(3,142)	(5,208)
Income (loss) before income tax provision and earnings from unconsolidated affiliates	(51,305)	7,991	(44,196)	24,624
Income tax benefit (expense)	6,983	(794)	6,584	(4,085)
Earnings from unconsolidated affiliates, net of tax	376	454	389	564
Earnings (losses) from consolidated affiliates, net of tax	(36)	(1,491)	(34)	(2,858)
Net income (loss)	(43,982)	6,160	(37,257)	18,245
Other comprehensive income (loss)
Postretirement medical plan amortization of prior service cost	313	247	626	494
Income tax on postretirement medical plan	(116)	(89)	(232)	(178)
Other comprehensive income (loss)	197	158	394	316
Total comprehensive income (loss)	(43,785)	6,318	(36,863)	18,561
Non-Guarantor Subsidiaries
Supplemental Condensed Consolidating Statement of Operations and Comprehensive Income
Revenue	0	5,592	0	9,557
Costs and expenses
Cost of product sold (exclusive of depreciation, depletion, amortization, and accretion, shown separately)	0	6,736	0	11,909
Depreciation and depletion	0	(22)	0	(240)
Amortization of port access contract rights	0	0	0	0
Accretion	0	1,016	0	2,032
Derivative financial instruments	0	0	0	0
Selling, general and administrative expenses	0	0	0	0
Goodwill impairment	0		0	0
Other operating costs	0	0	0	0
Total costs and expenses	0	7,730	0	13,701
Operating income (loss)	0	(2,138)	0	(4,144)
Other income (expense)
Interest income	0	0	0	0
Interest expense	(86)	(100)	(171)	(199)
Other, net	44	117	131	204
Total other income (expense)	(42)	17	(40)	5
Income (loss) before income tax provision and earnings from unconsolidated affiliates	(42)	(2,121)	(40)	(4,139)
Income tax benefit (expense)	6	630	6	1,281
Earnings from unconsolidated affiliates, net of tax	0	0	0	0
Earnings (losses) from consolidated affiliates, net of tax	0	0	0	0
Net income (loss)	(36)	(1,491)	(34)	(2,858)
Other comprehensive income (loss)
Postretirement medical plan amortization of prior service cost	0	0	0	0
Income tax on postretirement medical plan	0	0	0	0
Other comprehensive income (loss)	0	0	0	0
Total comprehensive income (loss)	$ (36)	$ (1,491)	$ (34)	$ (2,858)