Common and Preferred Stock - Additional Information (Detail) (USD $)	1 Months Ended	12 Months Ended
	Oct. 31, 2012	Dec. 31, 2012	Dec. 31, 2011
Stockholders Equity Note [Line Items]
Increase in share repurchase authorized amount	$ 200,000,000
Purchase of common stock (in shares)		2,182,946
Purchase of common stock		$ 89,563,000
Common stock, shares authorized		150,000,000	150,000,000
Common stock, par value		$ 0.01	$ 0.01
Preferred stock, shares authorized		5,000,000	5,000,000
Preferred stock, par value		$ 0.01	$ 0.01
Preferred stock, shares issued