Financial Instruments - Quantitative Information about Level 3 Fair Value Measurements (Parenthetical) (Detail)	Jun. 30, 2014
Auction Rate Preferred Securities [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
U.S. Treasury rate	1.24%
Municipal Securities [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair value assumption discount rate range of spread rate on treasury securities	175.00%
U.S. Treasury rate	1.43%
Student Loan Auction Rate Securities [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair value assumption discount rate range of spread rate on treasury securities	1.20%
U.S. Treasury rate	2.13%
Minimum [Member] | Auction Rate Preferred Securities [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair value assumption discount rate range of spread rate on treasury securities	110.00%
Maximum [Member] | Auction Rate Preferred Securities [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair value assumption discount rate range of spread rate on treasury securities	150.00%