Derivative Financial Instruments (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2016	Dec. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Aggregate fair value of derivative instruments with credit-risk-related contingent features, in case of net liability position	$ 77,578	$ 76,107
Collateral related to the derivatives	33,155	45,940
Fair value of assets required to settle the derivatives in, net liability position	44,422
Amount of unrestricted cash collateral to counterparties in the normal course of business	33,155	50,924
Cash collateral received	22,450	19,060
Net derivative gains estimated to be reclassified from accumulated other comprehensive income (loss) into net income within the next twelve months	4,651
Derivative financial instruments
Notional amount	3,835,242	1,788,922
Net derivatives, Fair value	15,897	(7,773)
Asset derivatives, Fair value	91,534	68,600
Liability derivatives, Fair value	75,637	76,373
Interest rate swaps
Derivative financial instruments
Average notional amount of the derivative instruments	620,400	443,589
Cross-currency swaps
Derivative financial instruments
Average notional amount of the derivative instruments	1,050,124	937,242
Other forward contracts
Derivative financial instruments
Average notional amount of the derivative instruments	1,324,717	5,014,845
Future
Derivative financial instruments
Average notional amount of the derivative instruments	165,772	111,801
Swaption
Derivative financial instruments
Average notional amount of the derivative instruments	146,329	212,299
Derivatives designated as hedges:
Derivative financial instruments
Notional amount	809,094	524,673
Net derivatives, Fair value	36,961	40,557
Asset derivatives, Fair value	43,859	40,579
Liability derivatives, Fair value	6,898	22
Derivatives designated as hedges: \| Cash flow hedges:
Derivative financial instruments
Notional amount	809,094	524,673
Net derivatives, Fair value	36,961	40,557
Asset derivatives, Fair value	43,859	40,579
Liability derivatives, Fair value	6,898	22
Derivatives designated as hedges: \| Cash flow hedges: \| Interest rate swaps
Derivative financial instruments
Notional amount	419,800	143,800
Net derivatives, Fair value	11,443	11,843
Asset derivatives, Fair value	13,867	11,843
Liability derivatives, Fair value	2,424	0
Derivatives designated as hedges: \| Cash flow hedges: \| Cross-currency swaps
Derivative financial instruments
Notional amount	389,294	380,873
Net derivatives, Fair value	25,518	28,714
Asset derivatives, Fair value	29,992	28,736
Liability derivatives, Fair value	4,474	22
Derivatives not designated as hedges:
Derivative financial instruments
Notional amount	3,026,148	1,264,249
Net derivatives, Fair value	(21,064)	(48,330)
Asset derivatives, Fair value	47,675	28,021
Liability derivatives, Fair value	68,739	76,351
Derivatives not designated as hedges: \| Interest rate swaps
Derivative financial instruments
Notional amount	361,100	303,600
Net derivatives, Fair value	13,850	3,240
Asset derivatives, Fair value	21,619	8,295
Liability derivatives, Fair value	7,769	5,055
Derivatives not designated as hedges: \| Cross-currency swaps
Derivative financial instruments
Notional amount	662,935	662,935
Net derivatives, Fair value	(38,149)	(51,759)
Asset derivatives, Fair value	21,716	19,537
Liability derivatives, Fair value	59,865	71,296
Derivatives not designated as hedges: \| Futures on equity indices
Derivative financial instruments
Notional amount	32,259	29,310
Net derivatives, Fair value	0	0
Asset derivatives, Fair value	0	0
Liability derivatives, Fair value	0	0
Derivatives not designated as hedges: \| Interest rate futures
Derivative financial instruments
Notional amount	137,500	117,200
Net derivatives, Fair value	0	0
Asset derivatives, Fair value	0	0
Liability derivatives, Fair value	0	0
Derivatives not designated as hedges: \| Interest rate swaptions
Derivative financial instruments
Notional amount	144,704	151,204
Net derivatives, Fair value	179	189
Asset derivatives, Fair value	179	189
Liability derivatives, Fair value	0	$ 0
Derivatives not designated as hedges: \| Other forward contracts
Derivative financial instruments
Notional amount	1,687,650
Net derivatives, Fair value	3,056
Asset derivatives, Fair value	4,161
Liability derivatives, Fair value	$ 1,105

Average notional amount specified by the derivative(s). Expressed as an absolute value.

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The estimated value of gains (losses), net anticipated to be transferred in the next twelve months from accumulated other comprehensive income into earnings.

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Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

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-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
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The aggregate fair value of assets needed to immediately settle the derivative instruments with credit-risk-related contingent features if the credit-risk-related contingent features were triggered at the end of the reporting period.

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The aggregate fair value of assets that are already posted, at the end of the reporting period, as collateral for derivative instruments with credit-risk-related contingent features.

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Amount of obligation to return cash collateral under master netting arrangements that have not been offset against derivative assets.

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Amount of right to receive cash collateral under master netting arrangements that have not been offset against derivative liabilities.

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Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

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Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

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Fair value of the assets less the liabilities of a derivative or group of derivatives.

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The aggregate fair value amounts of derivative instruments that contain credit-risk-related contingent features that are in a net liability position at the end of the reporting period. For nonderivative instruments that are designated and qualify as hedging instruments, the fair value amounts are the carrying value of the nonderivative hedging instrument, including the adjustment for the foreign currency transaction gain (loss) on that instrument.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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