Guarantees and Indemnifications (Detail) $ in Thousands	Dec. 31, 2018 USD ($)
Guarantor Obligations [Line Items]
Guarantees and Indemnifications Outstanding Amount, Expires Within One Year	$ 176,128
Guarantees and Indemnifications Outstanding Amount, Expires After One Year	56,053
Guarantees and Indemnifications, Total Outstanding Amount	232,181
Guarantees and Indemnifications, Maximum Potential Amount of Future Payments	508,121
Financial stand-by letters of credit
Guarantor Obligations [Line Items]
Guarantees and Indemnifications Outstanding Amount, Expires Within One Year	169,242
Guarantees and Indemnifications Outstanding Amount, Expires After One Year	55,563
Guarantees and Indemnifications, Total Outstanding Amount	224,805
Guarantees and Indemnifications, Maximum Potential Amount of Future Payments	444,066
Performance stand-by letters of credit
Guarantor Obligations [Line Items]
Guarantees and Indemnifications Outstanding Amount, Expires Within One Year	3,614
Guarantees and Indemnifications, Total Outstanding Amount	3,614
Guarantees and Indemnifications, Maximum Potential Amount of Future Payments	3,665
Commercial Letters of Credit
Guarantor Obligations [Line Items]
Guarantees and Indemnifications Outstanding Amount, Expires Within One Year	3,272
Guarantees and Indemnifications Outstanding Amount, Expires After One Year	490
Guarantees and Indemnifications, Total Outstanding Amount	3,762
Guarantees and Indemnifications, Maximum Potential Amount of Future Payments	$ 60,390