Fair Value Measurements - Quantitative Information about Level 3 Fair Value Measurements (Parenthetical) (Detail) - USD ($)	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Fair Value, Option, Quantitative Disclosures [Line Items]
Impaired loans	$ 8,000,000		$ 8,000,000
Level 3 [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Impaired loans	8,000,000		8,000,000
Level 3 [Member] | Nonrecurring [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Impaired loans	$ 8,000,000		$ 8,000,000
Level 3 [Member] | Nonrecurring [Member] | Maximum [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Impaired loans		$ 1,000,000