Schedule of Fair Value Assets and Liabilities Measured on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Mar. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value of plan assets	$ 9,072	$ 9,915
Supplemental Executive Retirement Plan
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of plan assets	9,267	10,038
Other pending transactions	(195)	(123)
Total fair value of plan assets	9,072	9,915
Supplemental Executive Retirement Plan | Quoted Prices In Active Markets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of plan assets	8,137	9,184
Other pending transactions	(195)	(123)
Total fair value of plan assets	7,942	9,061
Supplemental Executive Retirement Plan | Significant Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of plan assets	1,130	854
Total fair value of plan assets	1,130	854
Supplemental Executive Retirement Plan | Common stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of plan assets	3,497	3,859
Supplemental Executive Retirement Plan | Common stock | Quoted Prices In Active Markets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of plan assets	3,497	3,859
Supplemental Executive Retirement Plan | Foreign Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of plan assets	258	201
Supplemental Executive Retirement Plan | Foreign Stock | Quoted Prices In Active Markets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of plan assets	258	201
Supplemental Executive Retirement Plan | American Depository Receipts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of plan assets	1,529	1,685
Supplemental Executive Retirement Plan | American Depository Receipts | Quoted Prices In Active Markets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of plan assets	1,529	1,685
Supplemental Executive Retirement Plan | Preferred American Depository Receipts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of plan assets	15	15
Supplemental Executive Retirement Plan | Preferred American Depository Receipts | Quoted Prices In Active Markets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of plan assets	15	15
Supplemental Executive Retirement Plan | Real Estate Investment Trusts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of plan assets	74	59
Supplemental Executive Retirement Plan | Real Estate Investment Trusts | Quoted Prices In Active Markets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of plan assets	74	59
Supplemental Executive Retirement Plan | Government Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of plan assets	1,818	1,926
Supplemental Executive Retirement Plan | Government Debt Securities | Quoted Prices In Active Markets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of plan assets	1,028	1,377
Supplemental Executive Retirement Plan | Government Debt Securities | Significant Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of plan assets	790	549
Supplemental Executive Retirement Plan | Open Ended Mutual Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of plan assets	1,770	1,916
Supplemental Executive Retirement Plan | Open Ended Mutual Funds | Quoted Prices In Active Markets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of plan assets	1,770	1,916
Supplemental Executive Retirement Plan | Cash and Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of plan assets	306	377
Supplemental Executive Retirement Plan | Cash and Cash Equivalents | Quoted Prices In Active Markets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of plan assets	(34)	72
Supplemental Executive Retirement Plan | Cash and Cash Equivalents | Significant Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of plan assets	$ 340	$ 305