Investments - Additional Information (Detail) (USD $) In Millions, unless otherwise specified				12 Months Ended		12 Months Ended		12 Months Ended
	Dec. 31, 2013	Sep. 01, 2013	Dec. 31, 2013 Chem-Mod Clean-Coal Venture - U.S. And Canadian Operations [Member]	Dec. 31, 2013 Chem-Mod Clean-Coal Venture [Member]	Dec. 31, 2013 Chem-Mod International LLC [Member]	Dec. 31, 2013 C-Quest Technology LLC [Member]	Aug. 01, 2013 C-Quest Technology LLC [Member]	Dec. 31, 2013 C-Quest Technology LLC [Member] Change In Option On Delivery Of Additional Interest [Member]
Schedule of Equity Method Investments [Line Items]
Ownership interest held	50.00%	99.00%	46.54%		31.52%	8.00%
Total assets of variable interest entities				$ 8.0
Total liabilities of variable interest entities				0.8
Total revenue of limited liability companies				37.9
Total expenses of limited liability companies				21.2
Non-controlling interest				19.2
Options to acquire additional interest, percent						19.00%		15.00%
Options to acquire additional interest, total price						9.5		7.5
End date for acquiring additional interest						Aug. 15, 2016
Loans to majority owners							$ 2.0
Interest rate of loan							2.00%
Maturity date of of loan						May 15, 2014
Loan description						On August 1, 2013, we loaned the majority owner $2.0 million at a 2% interest rate, which matures on May 15, 2014. The loan can be paid in cash or by delivery of an additional 4% ownership interest in C-Quest’s global operations. If the loan is paid by delivery of the additional 4% ownership interest, our option would be reduced to 15% and the remaining purchase price would be reduced to $7.5 million.
Delivery of additional ownership interest						4.00%