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Fair Value Measurements - Quantitative Information about Level 3 Fair Value Measurements (Parenthetical) (Detail) (Level 3 [Member])
Dec. 31, 2013
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 2.45%
Auction Rate Securities [Member] | 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 1.50%
Auction Rate Preferred Securities [Member]
  
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]  
U.S. Treasury rate 1.25%
Auction Rate Preferred Securities [Member] | Minimum [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%
Auction Rate Preferred Securities [Member] | Maximum [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%