Derivative Financial Instruments (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014
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		$ 76,107	$ 141,653
Collateral related to the derivatives		45,940	106,110
Fair value of assets required to settle the derivatives in, net liability position		30,167
Amount of unrestricted cash collateral to counterparties in the normal course of business		50,924	106,110
Collateral under derivative counterparty collateral agreements		19,060	791
Net derivative gains estimated to be reclassified from accumulated other comprehensive income (loss) into net income within the next twelve months		9,411
Derivative financial instruments
Notional amount		1,788,922	1,544,907
Net derivatives, Fair value		(7,773)	(100,983)
Asset derivatives, Fair value	[1]	68,600	35,604
Liability derivatives, Fair value	[1]	76,373	136,587
Interest rate swaps
Derivative financial instruments
Average notional amount of the derivative instruments		443,589	340,262
Other forward contracts
Derivative financial instruments
Average notional amount of the derivative instruments		5,014,845	4,217,408
Cross-currency swaps
Derivative financial instruments
Average notional amount of the derivative instruments		937,242	732,581
Futures
Derivative financial instruments
Average notional amount of the derivative instruments		111,801	21,702
Swaption
Derivative financial instruments
Average notional amount of the derivative instruments		212,299	407,552
Derivatives designated as hedges
Derivative financial instruments
Notional amount		524,673	436,445
Net derivatives, Fair value		40,557	21,574
Asset derivatives, Fair value	[1]	40,579	24,526
Liability derivatives, Fair value	[1]	22	2,952
Derivatives designated as hedges | Cash flow hedges
Derivative financial instruments
Notional amount		524,673	358,445
Net derivatives, Fair value		40,557	20,068
Asset derivatives, Fair value	[1]	40,579	22,889
Liability derivatives, Fair value	[1]	22	2,821
Derivatives designated as hedges | Cash flow hedges | Interest rate swaps
Derivative financial instruments
Notional amount		143,800	184,200
Net derivatives, Fair value		11,843	17,746
Asset derivatives, Fair value	[1]	11,843	17,746
Derivatives designated as hedges | Cash flow hedges | Cross-currency swaps
Derivative financial instruments
Notional amount		380,873	174,245
Net derivatives, Fair value		28,714	2,322
Asset derivatives, Fair value	[1]	28,736	5,143
Liability derivatives, Fair value	[1]	22	2,821
Derivatives designated as hedges | Fair value hedges
Derivative financial instruments
Notional amount			78,000
Net derivatives, Fair value			1,506
Asset derivatives, Fair value	[1]		1,637
Liability derivatives, Fair value	[1]		131
Derivatives designated as hedges | Fair value hedges | Interest rate swaps
Derivative financial instruments
Notional amount			78,000
Net derivatives, Fair value			1,506
Asset derivatives, Fair value	[1]		1,637
Liability derivatives, Fair value	[1]		131
Derivatives not designated as hedges
Derivative financial instruments
Notional amount		1,264,249	1,108,462
Net derivatives, Fair value		(48,330)	(122,557)
Asset derivatives, Fair value	[1]	28,021	11,078
Liability derivatives, Fair value	[1]	76,351	133,635
Derivatives not designated as hedges | Interest rate swaps
Derivative financial instruments
Notional amount		303,600	128,100
Net derivatives, Fair value		3,240	4,402
Asset derivatives, Fair value	[1]	8,295	6,246
Liability derivatives, Fair value	[1]	5,055	1,844
Derivatives not designated as hedges | Futures on equity indices
Derivative financial instruments
Notional amount		29,310	5,505
Derivatives not designated as hedges | Interest rate futures
Derivative financial instruments
Notional amount		117,200	17,958
Derivatives not designated as hedges | Interest rate swaptions
Derivative financial instruments
Notional amount		151,204	293,964
Net derivatives, Fair value		189	271
Asset derivatives, Fair value	[1]	189	271
Derivatives not designated as hedges | Cross-currency swaps
Derivative financial instruments
Notional amount		662,935	662,935
Net derivatives, Fair value		(51,759)	(127,230)
Asset derivatives, Fair value	[1]	19,537	4,561
Liability derivatives, Fair value	[1]	$ 71,296	$ 131,791

[1] The estimated fair value excludes accrued income and expense. The estimated fair value of all derivatives in an asset position is reported within other assets and the estimated fair value of all derivatives in a liability position is reported within other liabilities in the consolidated balance sheets.