Share-Based Compensation - Additional Information (Detail) (USD $)	1 Months Ended			9 Months Ended	1 Months Ended	9 Months Ended
	May 31, 2013	Jan. 31, 2013	Sep. 30, 2013	Sep. 30, 2013 Directors Stock Compensation Plan [Member]	Jan. 31, 2013 Performance Incentive Plan [Member]	Sep. 30, 2013 Performance Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Amortization of expense equally over a service period				1 year
Non-employee directors annual retainer, in shares	857
Unrecognized compensation expense related to the DSCP awards			$ 288,000
Granted awards, shares				9,427	23,491	23,491
Vesting period		3 years
Intrinsic value of PIP awards						$ 4,200,000