Stock Incentive Plans - Summary of Activity for Restricted Stock Unit, Long-Term Incentive Award and Non-Employee Director Stock Compensation (Detail) (Restricted Stock Units [Member], USD $) In Thousands, except Per Share data, unless otherwise specified	9 Months Ended
	Sep. 30, 2013
Restricted Stock Units [Member]
Summary of activity for restricted stock units, long-term incentive awards and non-employee director stock compensation
Number of Shares - Nonvested at December 31, 2012	1,292
Number of Shares - Granted	677
Number of Shares - Vested	(972)
Number of Shares - Canceled or expired	(49)
Number of Shares - Nonvested at September 30, 2013	948
Weighted Average Grant Date Fair Value - Nonvested at December 31, 2012	$ 5.38
Weighted Average Grant Date Fair Value - Granted	$ 1.89
Weighted Average Grant Date Fair Value - Vested	$ 4.50
Weighted Average Grant Date Fair Value - Canceled or expired	$ 6.55
Weighted Average Grant Date Fair Value - Nonvested at September 30, 2013	$ 3.67