Financial Derivatives - Outstanding Foreign Currency Forward Contracts, Options and Embedded Derivatives (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Derivatives Designated as Hedging Instruments under ASC 815 [Member] | Cash Flow Hedges [Member] | Option Contracts [Member] | US Dollars/Philippine Pesos [Member]
Derivative [Line Items]
Notional Amount	$ 17,250	$ 26,250
Settle Through Date	Dec. 31, 2019	Dec. 31, 2019
Derivatives Designated as Hedging Instruments under ASC 815 [Member] | Cash Flow Hedges [Member] | Forwards [Member] | US Dollars/Philippine Pesos [Member]
Derivative [Line Items]
Notional Amount	$ 21,000	$ 39,000
Settle Through Date	Sep. 30, 2019	Sep. 30, 2019
Derivatives Designated as Hedging Instruments under ASC 815 [Member] | Cash Flow Hedges [Member] | Forwards [Member] | US Dollars/Costa Rican Colones [Member]
Derivative [Line Items]
Notional Amount	$ 46,000	$ 67,000
Settle Through Date	Dec. 31, 2019	Dec. 31, 2019
Derivatives Not Designated as Hedging Instruments under ASC 815 [Member] | Forwards [Member]
Derivative [Line Items]
Notional Amount	$ 17,000	$ 19,261
Settle Through Date	Nov. 30, 2021	Nov. 30, 2021
Derivatives Not Designated as Hedging Instruments under ASC 815 [Member] | Embedded Derivatives [Member]
Derivative [Line Items]
Notional Amount		$ 14,069
Settle Through Date		Apr. 30, 2030