(9) Other long-term assets and other income (loss) (Detail) - Other long-term assets and other income (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011
Long-term assets:
Advance coal royalties	$ 3,324		$ 3,205
Deferred financing costs, net	1,494		295
Marketable equity securities available for sale at fair value (restricted)*	3,548	[1]	2,326	[1]
Miscellaneous	2,941		468
	11,307		6,294
Other income:
MSHA reimbursements**	4,236	[2]	1,900	[2]
Miscellaneous	460		405
	$ 4,696		$ 2,305

[1] Held by Sunrise Indemnity, Inc., our wholly-owned captive insurance company.

[2] See "MSHA Reimbursements" in our MD&A section for a discussion of the $1.9 million.