Financial Derivatives and Hedging Activities - Outstanding Derivatives Used to Hedge Foreign Exchange Risks (Detail)	Dec. 31, 2020 USD ($)	Dec. 31, 2020 EUR (€)	Dec. 31, 2020 PHP (₱)	Dec. 31, 2020 CAD ($)	Dec. 31, 2020 GBP (£)	Dec. 31, 2019 USD ($)	Dec. 31, 2019 EUR (€)	Dec. 31, 2019 PHP (₱)	Dec. 31, 2019 CAD ($)	Dec. 31, 2019 GBP (£)
Cash Flow Hedges [Member] | Euro / British Pound [Member] | Designated as Hedging [Member] | Sell Notional [Member]
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative notional amount | €		€ 18,638,000					€ 17,702,000
Cash Flow Hedges [Member] | Philippine Peso / Euro [Member] | Designated as Hedging [Member] | Sell Notional [Member]
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative notional amount | €		18,522,000
Cash Flow Hedges [Member] | Euro / Philippine Peso [Member] | Designated as Hedging [Member] | Buy Notional [Member]
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative notional amount | ₱			₱ 853,686,000					₱ 1,039,432,000
Cash Flow Hedges [Member] | U.S Dollar / Euro [Member] | Designated as Hedging [Member] | Sell Notional [Member]
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative notional amount	$ 1,041,000					$ 5,347,000
Cash Flow Hedges [Member] | Canadian Dollar / U.S. Dollar [Member] | Designated as Hedging [Member] | Sell Notional [Member]
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative notional amount	70,000
Cash Flow Hedges [Member] | Canadian Dollar / U.S. Dollar [Member] | Designated as Hedging [Member] | Buy Notional [Member]
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative notional amount						1,523,000
Cash Flow Hedges [Member] | British Pound / Philippine Peso [Member] | Designated as Hedging [Member] | Buy Notional [Member]
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative notional amount | ₱			₱ 1,081,791,000					₱ 1,077,871,000
Cash Flow Hedges [Member] | U.S. Dollar / Canadian Dollar [Member] | Designated as Hedging [Member] | Sell Notional [Member]
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative notional amount						1,523,000
Cash Flow Hedges [Member] | U.S. Dollar / Canadian Dollar [Member] | Designated as Hedging [Member] | Buy Notional [Member]
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative notional amount				$ 34,847,000					$ 34,094,000
Cash Flow Hedges [Member] | Euro / U.S. Dollar [Member] | Designated as Hedging [Member] | Buy Notional [Member]
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative notional amount	69,324,000					82,317,000
Foreign Currency Hedges [Member] | Euro / British Pound [Member]
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative notional amount | €		€ 600,000
Foreign Currency Hedges [Member] | Euro / U.S. Dollar [Member] | Not Designated as Hedging [Member] | Buy Notional [Member]
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative notional amount	7,500,000					8,000,000
Foreign Currency Hedges [Member] | U.S. Dollar / British Pound [Member] | Not Designated as Hedging [Member] | Sell Notional [Member]
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative notional amount	$ 25,250,000					$ 25,500,000
Foreign Currency Hedges [Member] | British Pound / Euro [Member] | Not Designated as Hedging [Member] | Sell Notional [Member]
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative notional amount | £					£ 1,900,000					£ 3,000,000
Foreign Currency Hedges [Member] | British Pound / Euro [Member] | Not Designated as Hedging [Member] | Buy Notional [Member]
Derivative Instruments And Hedging Activities Disclosures [Line Items]
Derivative notional amount | €							€ 7,000,000