Employee Benefit Plans (Detail) (USD $)	3 Months Ended	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Other comprehensive income reclassification of defined benefit plan prior service cost and net actuarial loss		$ (464,000)
Defined benefit plan, contributions by employer	0
Other comprehensive income reclassification of defined benefit plan expected return on plan assets and net actuarial loss		50,000
Pension contributions	$ 0
Common stock, shares authorized (in shares)	40,000,000	40,000,000	40,000,000
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, equity instruments other than options, nonvested, number (in shares)	1,113,376	1,113,376