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Financial Derivatives and Hedging Activities - Outstanding Derivatives Used to Hedge Foreign Exchange Risks (Detail) | Sep. 30, 2016 USD ($) | Sep. 30, 2016 EUR (€) | Sep. 30, 2016 PHP | Sep. 30, 2016 CAD | Sep. 30, 2016 GBP (£) | Dec. 31, 2015 USD ($) | Dec. 31, 2015 EUR (€) | Dec. 31, 2015 PHP | Dec. 31, 2015 CAD | Dec. 31, 2015 GBP (£)
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Cash Flow Hedges [Member] | Euro / British Pound [Member] | Designated as Hedging [Member] | Sell/Buy - Sell Notional [Member] |  |  |  |  |  |  |  |  |  |
Derivative Instruments And Hedging Activities Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |
Derivative notional amount | € |  | € 7,703,000 |  |  |  |  | € 10,527,000 |  |  |
Cash Flow Hedges [Member] | Euro / Philippine Peso [Member] | Designated as Hedging [Member] | Sell/Buy - Buy Notional [Member] |  |  |  |  |  |  |  |  |  |
Derivative Instruments And Hedging Activities Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |
Derivative notional amount | PHP |  |  | PHP 733,358,000 |  |  |  |  | PHP 758,634,000 |  |
Cash Flow Hedges [Member] | British Pound / Philippine Peso [Member] | Designated as Hedging [Member] | Sell/Buy - Buy Notional [Member] |  |  |  |  |  |  |  |  |  |
Derivative Instruments And Hedging Activities Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |
Derivative notional amount | PHP |  |  | PHP 408,967,000 |  |  |  |  | PHP 542,063,000 |  |
Cash Flow Hedges [Member] | Euro / U.S. Dollar [Member] | Designated as Hedging [Member] | Sell/Buy - Buy Notional [Member] |  |  |  |  |  |  |  |  |  |
Derivative Instruments And Hedging Activities Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |
Derivative notional amount | $ | $ 42,672,000 |  |  |  |  | $ 51,433,000 |  |  |  |
Cash Flow Hedges [Member] | U.S. Dollar / Canadian Dollar [Member] | Designated as Hedging [Member] | Sell/Buy - Buy Notional [Member] |  |  |  |  |  |  |  |  |  |
Derivative Instruments And Hedging Activities Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |
Derivative notional amount | CAD |  |  |  | CAD 34,143,000 |  |  |  |  | CAD 34,649,000 |
Cash Flow Hedges [Member] | U.S Dollar / Euro [Member] | Designated as Hedging [Member] | Sell/Buy - Buy Notional [Member] |  |  |  |  |  |  |  |  |  |
Derivative Instruments And Hedging Activities Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |
Derivative notional amount | € |  | 26,774,000 |  |  |  |  |  |  |  |
Foreign Currency Hedges [Member] | Euro / U.S. Dollar [Member] | Not Designated as Hedging [Member] | Sell/Buy - Buy Notional [Member] |  |  |  |  |  |  |  |  |  |
Derivative Instruments And Hedging Activities Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |
Derivative notional amount | $ |  |  |  |  |  | 12,500,000 |  |  |  |
Foreign Currency Hedges [Member] | U.S. Dollar / British Pound [Member] | Not Designated as Hedging [Member] | Sell/Buy - Sell Notional [Member] |  |  |  |  |  |  |  |  |  |
Derivative Instruments And Hedging Activities Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |
Derivative notional amount | $ | $ 10,500,000 |  |  |  |  | $ 10,000,000 |  |  |  |
Foreign Currency Hedges [Member] | British Pound / Euro [Member] | Not Designated as Hedging [Member] | Sell/Buy - Sell Notional [Member] |  |  |  |  |  |  |  |  |  |
Derivative Instruments And Hedging Activities Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |
Derivative notional amount | £ |  |  |  |  | £ 2,500,000 |  |  |  |  | £ 3,500,000
Foreign Currency Hedges [Member] | British Pound / Euro [Member] | Not Designated as Hedging [Member] | Sell/Buy - Buy Notional [Member] |  |  |  |  |  |  |  |  |  |
Derivative Instruments And Hedging Activities Disclosures [Line Items] |  |  |  |  |  |  |  |  |  |
Derivative notional amount | € |  | € 18,500,000 |  |  |  |  | € 13,500,000 |  |  |

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