Equity Compensation - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Capitalization of stock-based compensation cost	$ 0	$ 0
Pre-tax compensation expense for unvested stock-based compensation grants	16,000
Service period applicable to the grantees on a weighted-average basis, years	1 year 7 months 6 days
Number of RSUs vested in the period that were settled in cash		48,935
RSUs vested and settled in shares of common stock, amount	1,003	2,754
RSUs vested and settled in cash, amount		$ 3,073