Fair Value Measurements - Financial Assets and Liabilities, Classified by Level (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Mar. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading investments for deferred compensation plan	$ 17,998	$ 15,043
Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	402,983	448,742
Trading investments for deferred compensation plan	17,998	15,043
Acquisition-related contingent consideration included in accrued and other current liabilities and other non-current liabilities	0	0
Fair Value, Measurements, Recurring | Level 1 | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Currency exchange derivative assets included in other current assets	0	0
Currency exchange derivative liabilities included in accrued and other current liabilities	0	0
Fair Value, Measurements, Recurring | Level 1 | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading investments for deferred compensation plan	4,229	2,813
Fair Value, Measurements, Recurring | Level 1 | Mutual funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading investments for deferred compensation plan	13,769	12,230
Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Trading investments for deferred compensation plan	0	0
Acquisition-related contingent consideration included in accrued and other current liabilities and other non-current liabilities	0	0
Fair Value, Measurements, Recurring | Level 2 | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Currency exchange derivative assets included in other current assets	235	48
Currency exchange derivative liabilities included in accrued and other current liabilities	1,392	443
Fair Value, Measurements, Recurring | Level 2 | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading investments for deferred compensation plan	0	0
Fair Value, Measurements, Recurring | Level 2 | Mutual funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading investments for deferred compensation plan	0	0
Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Trading investments for deferred compensation plan	0	0
Acquisition-related contingent consideration included in accrued and other current liabilities and other non-current liabilities	0	9,908
Fair Value, Measurements, Recurring | Level 3 | Foreign exchange contracts
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Currency exchange derivative assets included in other current assets	0	0
Currency exchange derivative liabilities included in accrued and other current liabilities	0	0
Fair Value, Measurements, Recurring | Level 3 | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading investments for deferred compensation plan	0	0
Fair Value, Measurements, Recurring | Level 3 | Mutual funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading investments for deferred compensation plan	$ 0	$ 0