Investment Securities (Gains and losses by category) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Available For Sale Securities Continuous Unrealized Loss Position Amortized Cost [Abstract]
Available for sale - Amortized cost - less than 12 month	$ 127,221	$ 148,896
Available for sale - Amortized cost - more than 12 month	567,531	220,334
Total Available for Sale Amortization cost	694,752	369,230
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available for sale - Unrealized Loss - less than 12 month	436	942
Available for sale - Unrealized Loss - more than 12 month	13,687	5,001
Total Available for Sale Unrealized Loss	14,123	5,943
Available For Sale Securities Continuous Unrealized Loss Position Fair Value [Abstract]
Available for sale - Fair Value - less than 12 month	126,785	147,954
Available-for-sale, Fair Value - more than 12 month	553,844	215,333
Total Available for Sale Fair Value	680,629	363,287
Continuous Unrealized Loss Position Amortized Cost [Abstract]
Held to Maturity - Amortized cost - less than 12 month	0	153,665
Held to Maturity - Amortized cost - more than 12 month	424,740	352,399
Held to Maturity - Amortized Cost	424,740	506,064
Held To Maturity Securities, Continuous Unrealized Loss Position Aggregate Losses [Abstract]
Held to Maturity- Unrealized Loss - less than 12 month	0	1,119
Held to Maturity- Unrealized Loss - more than 12 month	14,387	7,264
Held to Maturity- Unrealized Loss	14,387	8,383
Held To Maturity Securities Continuous Unrealized Loss Position Fair Value [Abstract]
Held-to-Maturity - Fair Value - less than 12 Month	0	152,546
Held-to-Maturity - Fair Value - more than 12 Month	410,353	345,135
Held to Maturity - Fair Value	410,353	497,681
Investment Securities Continuous Unrealized Loss Position [Abstract]
Investment Securities - Amortized Cost	1,119,492	875,294
Investment Securities - Fair Value	1,090,982	860,968
CMO's issued by us government sponsored agencies at loss
Available For Sale Securities Continuous Unrealized Loss Position Amortized Cost [Abstract]
Available for sale - Amortized cost - less than 12 month	0	9,464
Available for sale - Amortized cost - more than 12 month	66,230	72,562
Total Available for Sale Amortization cost	66,230	82,026
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available for sale - Unrealized Loss - less than 12 month	0	98
Available for sale - Unrealized Loss - more than 12 month	2,166	1,857
Total Available for Sale Unrealized Loss	2,166	1,955
Available For Sale Securities Continuous Unrealized Loss Position Fair Value [Abstract]
Available for sale - Fair Value - less than 12 month	0	9,366
Available-for-sale, Fair Value - more than 12 month	64,064	70,705
Total Available for Sale Fair Value	64,064	80,071
Obligation of Puerto Rico Government and public instrumentalities at loss
Available For Sale Securities Continuous Unrealized Loss Position Amortized Cost [Abstract]
Available for sale - Amortized cost - more than 12 month	0	2,455
Total Available for Sale Amortization cost	0	2,455
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available for sale - Unrealized Loss - more than 12 month		362
Total Available for Sale Unrealized Loss		362
Available For Sale Securities Continuous Unrealized Loss Position Fair Value [Abstract]
Available-for-sale, Fair Value - more than 12 month	0	2,093
Total Available for Sale Fair Value	0	2,093
FNMA and FHLMC [Member]
Available For Sale Securities Continuous Unrealized Loss Position Amortized Cost [Abstract]
Available for sale - Amortized cost - less than 12 month	109,772	125,107
Available for sale - Amortized cost - more than 12 month	357,955	111,635
Total Available for Sale Amortization cost	467,727	236,742
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available for sale - Unrealized Loss - less than 12 month	348	759
Available for sale - Unrealized Loss - more than 12 month	8,603	2,122
Total Available for Sale Unrealized Loss	8,951	2,881
Available For Sale Securities Continuous Unrealized Loss Position Fair Value [Abstract]
Available for sale - Fair Value - less than 12 month	109,424	124,348
Available-for-sale, Fair Value - more than 12 month	349,352	109,513
Total Available for Sale Fair Value	458,776	233,861
Continuous Unrealized Loss Position Amortized Cost [Abstract]
Held to Maturity - Amortized cost - less than 12 month	0	153,665
Held to Maturity - Amortized cost - more than 12 month	424,740	352,399
Held to Maturity - Amortized Cost	424,740	506,064
Held To Maturity Securities, Continuous Unrealized Loss Position Aggregate Losses [Abstract]
Held to Maturity- Unrealized Loss - less than 12 month	0	1,119
Held to Maturity- Unrealized Loss - more than 12 month	14,387	7,264
Held to Maturity- Unrealized Loss	14,387	8,383
Held To Maturity Securities Continuous Unrealized Loss Position Fair Value [Abstract]
Held-to-Maturity - Fair Value - less than 12 Month	0	152,546
Held-to-Maturity - Fair Value - more than 12 Month	410,353	345,135
Held to Maturity - Fair Value	410,353	497,681
Government National Mortgage Association Certificates and Obligations (GNMA) [Member]
Available For Sale Securities Continuous Unrealized Loss Position Amortized Cost [Abstract]
Available for sale - Amortized cost - less than 12 month	17,126	14,001
Available for sale - Amortized cost - more than 12 month	131,044	20,803
Total Available for Sale Amortization cost	148,170	34,804
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available for sale - Unrealized Loss - less than 12 month	88	85
Available for sale - Unrealized Loss - more than 12 month	2,739	499
Total Available for Sale Unrealized Loss	2,827	584
Available For Sale Securities Continuous Unrealized Loss Position Fair Value [Abstract]
Available for sale - Fair Value - less than 12 month	17,038	13,916
Available-for-sale, Fair Value - more than 12 month	128,305	20,304
Total Available for Sale Fair Value	145,343	34,220
Obligation of US Government sponsored agencies at loss [Member]
Available For Sale Securities Continuous Unrealized Loss Position Amortized Cost [Abstract]
Available for sale - Amortized cost - more than 12 month	2,325	2,927
Total Available for Sale Amortization cost	2,325	2,927
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available for sale - Unrealized Loss - more than 12 month	60	48
Total Available for Sale Unrealized Loss	60	48
Available For Sale Securities Continuous Unrealized Loss Position Fair Value [Abstract]
Available-for-sale, Fair Value - more than 12 month	2,265	2,879
Total Available for Sale Fair Value	2,265	2,879
US Treasury Securities at loss
Available For Sale Securities Continuous Unrealized Loss Position Amortized Cost [Abstract]
Available for sale - Amortized cost - less than 12 month	323	324
Available for sale - Amortized cost - more than 12 month	9,977	9,952
Total Available for Sale Amortization cost	10,300	10,276
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available for sale - Unrealized Loss - less than 12 month	0	0
Available for sale - Unrealized Loss - more than 12 month	119	113
Total Available for Sale Unrealized Loss	119	113
Available For Sale Securities Continuous Unrealized Loss Position Fair Value [Abstract]
Available for sale - Fair Value - less than 12 month	323	324
Available-for-sale, Fair Value - more than 12 month	9,858	9,839
Total Available for Sale Fair Value	$ 10,181	$ 10,163

Amortized cost of investments in available-for-sale securities that have been in a loss position.

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Amortized cost of investments in available-for-sale securities that have been in a loss position for less than twelve months.

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Amount of unrealized loss on securities classified as available-for-sale that have been in a loss position for twelve months or longer.

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Amortized cost of investments in available-for-sale securities that have been in a loss position for more than twelve months.

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Amortized cost of investments in held-to-maturity securities that have been in a loss position for less than twelve months.

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Held to maturity securities continuous unrealized loss position, amortized cost.

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Amortized cost of investments in held-to-maturity securities that have been in a loss position for more than twelve months.

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Amortized cost of investments in securities that have been in a loss position.

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This item represents the aggregate fair value of investments in debt and equity securities in an unrealized loss position which are categorized neither as held-to-maturity nor trading securities.

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Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity), in continuous loss position for 12 months or longer.

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Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity), in unrealized loss position.

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Fair value of investment in debt security measured at amortized cost (held-to-maturity), in unrealized loss position.

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