Stock-Based Compensation Plans - Additional Information (Detail) (USD $)	1 Months Ended	3 Months Ended					1 Months Ended	3 Months Ended		1 Months Ended	3 Months Ended
	Jan. 31, 2012 Stock Option and Incentive Plan 2003	Mar. 31, 2012 Management Stock Purchase Plan	Jun. 30, 2012 2003 and 2012 Stock Option and Incentive Plan	Jun. 30, 2012 2003 and 2012 Stock Option and Incentive Plan Minimum	Jun. 30, 2012 2003 and 2012 Stock Option and Incentive Plan Maximum	Sep. 30, 2012 Stock Option and Incentive Plan 2012	Feb. 28, 2012 Restricted Stock Stock Option and Incentive Plan 2003	Mar. 31, 2012 Performance Shares Long Term Performance Share Plan Twenty Zero Nine to Twenty Eleven	Mar. 31, 2012 Deferred Stock Awards Defined Contribution Retirement Plan	Jan. 31, 2012 Stock Options Stock Option and Incentive Plan 2003	Jun. 30, 2012 Stock Options 2003 and 2012 Stock Option and Incentive Plan	Sep. 30, 2012 Stock Options Stock Option and Incentive Plan 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation, option granted	2,000		3,000			3,500
Stock based compensation, expected volatility rate										53.34%
Stock based compensation, expected life										5 years
Stock based compensation, expected dividend rate										3.00%
Stock based compensation, risk free interest rate										0.89%
Stock based compensation, option granted, grant date fair value	$ 12.68			$ 12.07	$ 12.67	$ 13.85
Stock based compensation, vesting period							3 years			5 years	5 years	5 years
Stock based compensation, option granted, contractual life	10 years		10 years			10 years
Stock based compensation, shares granted		7,195					7,050		2,322
Stock based compensation, shares granted, grant date fair value							$ 35.76
Stock based compensation, number of shares vested								13,969