Components of Net Periodic Benefit Cost - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2014	Jun. 30, 2014	Dec. 31, 2006	Dec. 31, 2002
Compensation and Retirement Disclosure [Abstract]
Defined benefit plan age of attainment		21 years
Service period for employees of coverage age, years		1 year
Defined benefit plan, percentage vested	100.00%	100.00%
Benefits paid	$ 4.3	$ 4.3
Charge associated with employees that elected to receive lump sum pension distributions		$ 1.3
Retiree benefits eliminated if less than service period, years		10 years	10 years	10 years