Subsequent Events - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified			1 Months Ended	0 Months Ended
	Jun. 30, 2013	Dec. 31, 2012	Jul. 16, 2013 Subsequent Event	Aug. 08, 2013 Subsequent Event Director Compensation Program [Member]	Aug. 08, 2013 Subsequent Event For each Board Member Director Compensation Program [Member]	Jul. 16, 2013 Subsequent Event Minimum	Jul. 16, 2013 Subsequent Event Maximum
Subsequent Event [Line Items]
Common stock, shares authorized	665,000,000	665,000,000				190,000,000	665,000,000
Restricted stock issued			182,927
Shares of restricted common stock issued to nonexecutive Board members					24,805
Grant date fair value of restricted stock awards				$ 69