Valuation Techniques, Significant Unobservable Inputs, and Quantitative Information (Detail) (Fair Value, Inputs, Level 3, Auction Rate Securities, USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2014
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Financial instrument, fair value	$ 85.2
Group One
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Valuation Technique	Discounted Cash Flow
Unobservable Inputs	Remaining lives
Group Two
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Valuation Technique	Discounted Cash Flow
Unobservable Inputs	Discount rates
Lower Limit
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Financial instrument remaining lives	1 year 8 months 12 days
Financial instrument discount rate	0.20%
Upper Limit
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Financial instrument remaining lives	8 years 7 months 6 days
Financial instrument discount rate	7.90%