Supplemental Guarantor/Non-Guarantor Financial Information (Details 4) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Cash flows from continuing operations
Net cash provided by (used in) operating activities	$ 62,064	$ 42,115
Investing activities
Purchases of property, plant and equipment	(28,125)	(14,680)
Cash paid for capitalized interest	(404)	(4,066)
Investments in marketable securities	0	(8,159)
Maturity and redemption of investments	0	88,845
Investment in port access contract rights	0	(37,100)
Investment in development projects	(1,526)	(3,522)
Investment in unconsolidated affiliates	(5,383)	0
Payment of restricted cash	(6,500)	0
Other	185	(1,830)
Net cash provided by (used in) investing activities	(41,753)	19,488
Financing activities
Principal payments on federal coal leases	(63,970)	(58,958)
Issuance of senior notes	0	200,000
Repayment of senior notes	0	(300,000)
Payment of deferred financing costs	(342)	(14,683)
Other	(1,225)	(305)
Net cash provided by (used in) financing activities	(65,537)	(173,946)
Net increase (decrease) in cash and cash equivalents	(45,226)	(112,343)
Cash and cash equivalents at beginning of period	168,745	231,633
Cash and cash equivalents at end of period	123,519	119,290
Eliminations
Cash flows from continuing operations
Net cash provided by (used in) operating activities	0	0
Investing activities
Purchases of property, plant and equipment	0	0
Investments in marketable securities	0	0
Maturity and redemption of investments	0	0
Investment in development projects	0	0
Payment of restricted cash	0	0
Contributions made to subsidiary		1,750
Distribution received from subsidiary		(1,486)
Other	0	0
Net cash provided by (used in) investing activities	0	264
Financing activities
Issuance of senior notes	0	0
Repayment of senior notes	0	0
Payment of deferred financing costs	0	0
Contributions received from parent		(1,750)
Distributions made to parent		1,486
Other	0	0
Net cash provided by (used in) financing activities	0	(264)
Net increase (decrease) in cash and cash equivalents	0	0
Cash and cash equivalents at beginning of period	0	0
Cash and cash equivalents at end of period	0	0
Parent Guarantor (CPE Inc.)
Cash flows from continuing operations
Net cash provided by (used in) operating activities	0	(891)
Investing activities
Purchases of property, plant and equipment	0	0
Cash paid for capitalized interest	0	0
Investments in marketable securities	0	0
Maturity and redemption of investments	0	0
Investment in port access contract rights		0
Investment in development projects	0	0
Investment in unconsolidated affiliates	0
Payment of restricted cash	0	0
Contributions made to subsidiary		0
Distribution received from subsidiary		0
Other	0	0
Net cash provided by (used in) investing activities	0	0
Financing activities
Principal payments on federal coal leases	0	0
Issuance of senior notes	0	0
Repayment of senior notes	0	0
Payment of deferred financing costs	0	0
Contributions received from parent		0
Distributions made to parent		0
Other	0	891
Net cash provided by (used in) financing activities	0	891
Net increase (decrease) in cash and cash equivalents	0	0
Cash and cash equivalents at beginning of period	0	0
Cash and cash equivalents at end of period	0	0
Issuers
Cash flows from continuing operations
Net cash provided by (used in) operating activities	(43,653)	(71,744)
Investing activities
Purchases of property, plant and equipment	(2,827)	(3,012)
Cash paid for capitalized interest	0	0
Investments in marketable securities	0	(8,159)
Maturity and redemption of investments	0	88,845
Investment in port access contract rights		0
Investment in development projects	0	0
Investment in unconsolidated affiliates	0
Payment of restricted cash	0	0
Contributions made to subsidiary		0
Distribution received from subsidiary		0
Other	5	0
Net cash provided by (used in) investing activities	(2,822)	77,674
Financing activities
Principal payments on federal coal leases	0	0
Issuance of senior notes	0	200,000
Repayment of senior notes	0	(300,000)
Payment of deferred financing costs	(2)	(14,683)
Contributions received from parent		0
Distributions made to parent		0
Other	0	0
Net cash provided by (used in) financing activities	(2)	(114,683)
Net increase (decrease) in cash and cash equivalents	(46,477)	(108,753)
Cash and cash equivalents at beginning of period	167,532	226,993
Cash and cash equivalents at end of period	121,055	118,240
Guarantor Subsidiaries
Cash flows from continuing operations
Net cash provided by (used in) operating activities	105,717	119,157
Investing activities
Purchases of property, plant and equipment	(25,298)	(11,667)
Cash paid for capitalized interest	(404)	(4,066)
Investments in marketable securities	0	0
Maturity and redemption of investments	0	0
Investment in port access contract rights		(37,100)
Investment in development projects	(1,526)	(3,522)
Investment in unconsolidated affiliates	(5,383)
Payment of restricted cash	(6,500)	0
Contributions made to subsidiary		(1,750)
Distribution received from subsidiary		1,486
Other	180	(1,830)
Net cash provided by (used in) investing activities	(38,931)	(58,449)
Financing activities
Principal payments on federal coal leases	(63,970)	(58,958)
Issuance of senior notes	0	0
Repayment of senior notes	0	0
Payment of deferred financing costs	(339)	0
Contributions received from parent		0
Distributions made to parent		0
Other	(1,225)	(1,196)
Net cash provided by (used in) financing activities	(65,534)	(60,154)
Net increase (decrease) in cash and cash equivalents	1,252	554
Cash and cash equivalents at beginning of period	1,213	496
Cash and cash equivalents at end of period	2,465	1,050
Non-Guarantor Subsidiaries
Cash flows from continuing operations
Net cash provided by (used in) operating activities	0	(4,408)
Investing activities
Purchases of property, plant and equipment	0	0
Cash paid for capitalized interest	0	0
Investments in marketable securities	0	0
Maturity and redemption of investments	0	0
Investment in port access contract rights		0
Investment in development projects	0	0
Investment in unconsolidated affiliates	0
Payment of restricted cash	0	0
Contributions made to subsidiary		0
Distribution received from subsidiary		0
Other	0	0
Net cash provided by (used in) investing activities	0	0
Financing activities
Principal payments on federal coal leases	0	0
Issuance of senior notes	0	0
Repayment of senior notes	0	0
Payment of deferred financing costs	0	0
Contributions received from parent		1,750
Distributions made to parent		(1,486)
Other	0	0
Net cash provided by (used in) financing activities	0	264
Net increase (decrease) in cash and cash equivalents	0	(4,144)
Cash and cash equivalents at beginning of period	0	4,144
Cash and cash equivalents at end of period	$ 0	$ 0