Commitments and Contingencies - Commercial Commitments Outstanding (Detail) $ in Millions	Dec. 31, 2015 USD ($)
Commitments And Contingencies Disclosure [Abstract]
Total standby letters of credit	$ 80
Standby letters of credit due to expire in less than 1 year	77
Standby letters of credit due to expire in 1-3 years	0
Standby letters of credit due to expire in 3-5 years	0
Standby letters of credit due to expire after 5 years	$ 3