Stockholder Rights Plan - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012
Stock Based Compensation Activity [Line Items]
Portion of preferred share purchase right entitled to holder	0.001
Purchase price of Preferred Stock as per plan	150.00
Number of votes entitled to common stock	One
Price worth of surviving company common stock	$ 300.00
Percentage common stock to acquired to exercise stock rights	20.00%
Redemption price of stock holder rights plan	$ 0.01
Percentage of beneficial ownership	20.00%