Agreement With Roust Trading - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	1 Months Ended		9 Months Ended
	May 04, 2012	May 07, 2012	Sep. 30, 2012
Long-term Purchase Commitment [Line Items]
Interest rate percentage on issued debt			3.00%
Debt instrument issuance amount			70.0
Additional common stock issued to adjust issue price			3,000,000
Common stock issued on stockholders approval to adjust issue price			5,000,000
Common stock issued from escrow to adjust issue price			2,000,000
Repurchase Agreements [Member]
Long-term Purchase Commitment [Line Items]
Shares of common stock price			3.44
Repurchase Agreements [Member] | Maximum [Member]
Long-term Purchase Commitment [Line Items]
Common stock volume weighted average price			4.13
Repurchase Agreements [Member] | Minimum [Member]
Long-term Purchase Commitment [Line Items]
Common stock volume weighted average price			2.75
New Debt [Member]
Long-term Purchase Commitment [Line Items]
Debt instrument maturity date			Jul. 31, 2016
Senior Notes Due 2013 [Member]
Long-term Purchase Commitment [Line Items]
Common stock purchase price per share	$ 5.25
Roust Trading Limited [Member]
Long-term Purchase Commitment [Line Items]
Common stock issued under purchase agreement, shares	5,714,286
Common stock purchase value under purchase agreement		30
Common stock purchase price under purchase agreement	$ 5.25
Percentage of common stock in threshold			42.90%
Roust Trading Limited [Member] | Senior Notes Due 2013 [Member]
Long-term Purchase Commitment [Line Items]
Common stock issued under purchase agreement, shares	13,300,000
Senior notes purchased by affiliates		70
Senior notes purchased by affiliates due date		March 18, 2013
Interest rate percentage on issued debt	3.00%
Roust Trading Limited [Member] | Senior Rollover Notes Due 2013 [Member]
Long-term Purchase Commitment [Line Items]
Interest rate percentage on issued debt	6.00%
Debt instrument issuance amount	102.6
Debt instrument maturity date	Jul. 31, 2016
Roust Trading Limited [Member] | Senior Backstop Notes [Member]
Long-term Purchase Commitment [Line Items]
Interest rate percentage on issued debt	6.00%
Debt instrument issuance amount	107.5
Debt instrument maturity date	Jul. 31, 2016
Roust Trading Limited [Member] | Convertible Senior Notes Due 2013 [Member]
Long-term Purchase Commitment [Line Items]
Debt instrument issuance amount			102.6