Equity Compensation - Stock Options Granted, Forfeited, Exercised and Expired (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Number of shares
Number of Shares, Outstanding at beginning of period			1,574,604
Number of Shares, Granted	154,000	0	154,000	156,500
Number of Shares, Forfeited			(16,668)
Number of Shares, Exercised	0	93,911	0	197,965
Number of Shares, Expired			(286,494)
Number of Shares, Outstanding at end of period	1,425,442		1,425,442
Number of Shares, Exercisable at end of period	1,135,937		1,135,937
Weighted Average Exercise Price
Weighted Average Exercise Price, Outstanding at beginning of period			$ 84.90
Weighted Average Exercise Price, Granted			$ 19.31
Weighted Average Exercise Price, Forfeited			$ 75.11
Weighted Average Exercise Price, Exercised			$ 0.00
Weighted Average Exercise Price, Expired			$ 62.38
Weighted Average Exercise Price, Outstanding at end of period	$ 82.46		$ 82.46
Weighted Average Exercise Price, Exercisable at end of period	$ 92.16		$ 92.16
Aggregate Exercise Price
Aggregate Exercise Price, Outstanding at beginning of period			$ 133,691
Aggregate Exercise Price, Granted			2,974
Aggregate Exercise Price, Forfeited			(1,252)
Aggregate Exercise Price, Exercised			0
Aggregate Exercise Price, Expired			(17,871)
Aggregate Exercise Price, Outstanding at end of period	117,541		117,541
Aggregate Exercise Price, Exercisable at end of period	104,687		104,687
Weighted Average Remaining Contractual Term
Weighted Average Remaining Contractual Term, Outstanding at end of period, years			2 years 10 months 24 days
Weighted Average Remaining Contractual Term, Exercisable at end of period, years			2 years 7 months 6 days
Aggregate Intrinsic Value
Aggregate Intrinsic Value, Outstanding at end of period	784		784
Aggregate Intrinsic Value, Exercisable at end of period	$ 0		$ 0