Investment Securities (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Investments Guaranteed by US Treasury and Sponsored Agencies in Unrealized Loss on Position	$ 872,800
Investments Guaranteed by Puerto Rico Government and its Political Subdivisions in Unrealized Loss On Position	$ 2,500
Investments Guaranteed By Us Treasury And Sponsored Agencies in Unrealized Loss Position Percentage To Total Investment in Unrealized Loss Position	99.70%
Investments Guaranteed By Puerto Rico Government and Its Political Subdivisions in Unrealized Loss Position Percentage To Total Investment in Unrealized Loss Position	0.30%
Maximum GovernmentBond Probability Of Default	4.40%
Money market investments	$ 7,021	$ 5,606
Securitized GNMA pools retained, amortized cost	$ 74,900	$ 112,200
Securitized GNMA pool retained, yield	3.14%	2.89%
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities sold , Book Value	$ 250,100	$ 288,276	$ 101,259
Gain (Loss) on Sale of Securities, Net	6,896	12,207	2,572
Other Than Temporary Impairment Credit Losses Recognized In Earnings Credit Losses On Debt Securities Held	0	0	1,490	$ 0
Investments Guaranteed By Local Government And Its Political Subdivisions In Unrealized Loss On Position with Cumulative Default Probability Fair Value	$ 2,100
Investments Guaranteed By Local Government And Its Political Subdivisions In Unrealized Loss Position With Cumulative Default Percentage at Maturity	85.00%
Collateralized Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities sold , Book Value	$ 166,015	277,181	101,259
Collateralized Mortgage Backed Securities [Member] | FNMA and FHLMC [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities sold , Book Value	102,311	277,181	37,736
Collateralized Mortgage Backed Securities [Member] | Government National Mortgage Association Certificates and Obligations (GNMA) [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities sold , Book Value	63,704		$ 63,523
Collateralized Mortgage Backed Securities [Member] | Obligations of Puerto Rico Government and Public Instrumentalities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities sold , Book Value		$ 11,095
US Treasury Securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities sold , Book Value	$ 84,085