Expiration Years of Minimum Alternate Tax Credit (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Tax Credit Carryforward [Line Items]
Less: valuation allowance	$ 5,454	$ 2,616
Net deferred tax assets	37,786	$ 33,363
Minimum Alternate Tax (MAT)
Tax Credit Carryforward [Line Items]
Minimum Alternate Tax Credit	30,760
Less: valuation allowance	1,580
Net deferred tax assets	29,180
Minimum Alternate Tax (MAT) | 2017-18
Tax Credit Carryforward [Line Items]
Minimum Alternate Tax Credit	200
Minimum Alternate Tax (MAT) | 2018-19
Tax Credit Carryforward [Line Items]
Minimum Alternate Tax Credit	270
Minimum Alternate Tax (MAT) | 2019-20
Tax Credit Carryforward [Line Items]
Minimum Alternate Tax Credit	980
Minimum Alternate Tax (MAT) | 2020-21
Tax Credit Carryforward [Line Items]
Minimum Alternate Tax Credit	1,630
Minimum Alternate Tax (MAT) | 2021-22
Tax Credit Carryforward [Line Items]
Minimum Alternate Tax Credit	1,430
Minimum Alternate Tax (MAT) | 2022-23
Tax Credit Carryforward [Line Items]
Minimum Alternate Tax Credit	5,990
Minimum Alternate Tax (MAT) | 2023-24
Tax Credit Carryforward [Line Items]
Minimum Alternate Tax Credit	7,090
Minimum Alternate Tax (MAT) | 2024-25
Tax Credit Carryforward [Line Items]
Minimum Alternate Tax Credit	7,780
Minimum Alternate Tax (MAT) | 2025-26 [Member]
Tax Credit Carryforward [Line Items]
Minimum Alternate Tax Credit	$ 5,390