(6) Other Long-Term Assets and Other Income (Detail) - Other Long-Term Assets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013		Dec. 31, 2012
Long-term assets:
Advance coal royalties	$ 3,461		$ 3,324
Deferred financing costs, net	1,419		1,494
Marketable equity securities available for sale, at fair value (restricted)*	5,054	[1]	3,548	[1]
Miscellaneous	2,432		2,941
	$ 12,366		$ 11,307

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