Mergers and Acquisitions - Additional Information (Detail) (Alliance, USD $)	1 Months Ended
	May 03, 2012
Business Acquisition [Line Items]
Merger consideration cash per share	5.30
Merger consideration common stock per share	0.4435
Minimum
Business Acquisition [Line Items]
Shareholder's equity decline that will decrease merger consideration payable, percentage	10.00%
Maximum
Business Acquisition [Line Items]
Cash elections limit of common stock outstanding, percentage	20.00%