Equity Compensation - Stock Options Granted and Exercised (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
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Shares subject to stock options granted	154,000	0	154,000	156,500
Weighted average grant date fair value per share	$ 9.16	$ 0.00	$ 9.16	$ 31.36
Shares subject to stock options exercised	0	93,911	0	197,965
Intrinsic value of stock options exercised	$ 0	$ 2,299	$ 0	$ 4,788
Proceeds received from stock options exercised	0	3,423	0	8,091
Tax benefits realized from stock options exercised	$ 0	$ 733	$ 0	$ 1,597