Fair Value Measurements - Changes in Level 3 Securities (Detail) - USD ($) $ in Thousands |
9 Months Ended | |
---|---|---|
Sep. 30, 2019 |
Sep. 30, 2018 |
|
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] | ||
Beginning Balance | $ 82,600 | |
Purchases | 105,837 | |
Maturities/redemptions | (72,640) | |
Transfer to Level 2 | (4,459) | |
Amortization | (104) | |
Ending Balance | 111,234 | |
Auction Rate Securities [Member] | ||
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] | ||
Beginning Balance | 4,459 | |
Transfer to Level 2 | (4,459) | |
Obligations Issued by States and Political Subdivisions [Member] | ||
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] | ||
Beginning Balance | $ 88,728 | 78,141 |
Purchases | 13,290 | 105,837 |
Maturities/redemptions | (78,196) | (72,640) |
Amortization | (21) | (104) |
Ending Balance | $ 23,801 | $ 111,234 |