Investment Securities (Gains and losses by category) (Details) - USD ($)	3 Months Ended	12 Months Ended
Mar. 31, 2017	Dec. 31, 2016
Available For Sale Securities Continuous Unrealized Loss Position Amortized Cost [Abstract]
Available for sale - Amortized cost - less than 12 month	$ 315,912,000	$ 335,079,000
Available for sale - Amortized cost - more than 12 month	36,622,000	38,563,000
Total Available for Sale Amortization cost	352,534,000	373,642,000
Available For Sale Securities Continuous Unrealized Loss Position Aggregate Losses [Abstract]
Available for sale - Unrealized Loss - less than 12 month	4,483,000	5,723,000
Available for sale - Unrealized Loss - more than 12 month	997,000	1,400,000
Total Available for Sale Unrealized Loss	5,480,000	7,123,000
Available For Sale Securities Continuous Unrealized Loss Position Fair Value [Abstract]
Available for sale - Fair Value - less than 12 month	311,429,000	329,356,000
Available-for-sale, Fair Value - more than 12 month	35,625,000	37,163,000
Total Available for Sale Fair Value	347,054,000	366,519,000
Continuous Unrealized Loss Position Amortized Cost [Abstract]
Held to Maturity - Amortized cost - less than 12 month	501,949,000	525,258,000
Held to Maturity - Amortized Cost	501,949,000	525,258,000
Held To Maturity Securities, Continuous Unrealized Loss Position Aggregate Losses [Abstract]
Held to Maturity- Unrealized Loss - less than 12 month	7,152,000	7,266,000
Held to Maturity- Unrealized Loss	7,152,000	7,266,000
Held To Maturity Securities Continuous Unrealized Loss Position Fair Value [Abstract]
Held-to-Maturity - Fair Value - less than 12 Month	494,797,000	517,992,000
Held to Maturity - Fair Value	494,797,000	517,992,000
Investment Securities Continuous Unrealized Loss Position [Abstract]
Investment Securities - Amortized Cost	854,483,000	898,900,000
Investment Securities - Unrealized Loss	12,632,000	14,389,000
Investment Securities - Fair Value	841,851,000	884,511,000
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	55,117,000	67,777,000
Available for sale - Amortized cost - more than 12 month	31,942,000	33,883,000
Total Available for Sale Amortization cost	87,059,000	101,660,000
Available For Sale Securities Continuous Unrealized Loss Position Aggregate Losses [Abstract]
Available for sale - Unrealized Loss - less than 12 month	1,046,000	1,430,000
Available for sale - Unrealized Loss - more than 12 month	564,000	793,000
Total Available for Sale Unrealized Loss	1,610,000	2,223,000
Available For Sale Securities Continuous Unrealized Loss Position Fair Value [Abstract]
Available for sale - Fair Value - less than 12 month	54,071,000	66,347,000
Available-for-sale, Fair Value - more than 12 month	31,378,000	33,090,000
Total Available for Sale Fair Value	85,449,000	99,437,000
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	4,680,000	4,680,000
Total Available for Sale Amortization cost	4,680,000	4,680,000
Available For Sale Securities Continuous Unrealized Loss Position Aggregate Losses [Abstract]
Available for sale - Unrealized Loss - more than 12 month	433,000	607,000
Total Available for Sale Unrealized Loss	433,000	607,000
Available For Sale Securities Continuous Unrealized Loss Position Fair Value [Abstract]
Available-for-sale, Fair Value - more than 12 month	4,247,000	4,073,000
Total Available for Sale Fair Value	4,247,000	4,073,000
FNMA and FHLMC [Member]
Available For Sale Securities Continuous Unrealized Loss Position Amortized Cost [Abstract]
Available for sale - Amortized cost - less than 12 month	177,258,000	184,782,000
Total Available for Sale Amortization cost	177,258,000	184,782,000
Available For Sale Securities Continuous Unrealized Loss Position Aggregate Losses [Abstract]
Available for sale - Unrealized Loss - less than 12 month	2,165,000	3,036,000
Total Available for Sale Unrealized Loss	2,165,000	3,036,000
Available For Sale Securities Continuous Unrealized Loss Position Fair Value [Abstract]
Available for sale - Fair Value - less than 12 month	175,093,000	181,746,000
Total Available for Sale Fair Value	175,093,000	181,746,000
Continuous Unrealized Loss Position Amortized Cost [Abstract]
Held to Maturity - Amortized cost - less than 12 month	501,949,000	525,258,000
Held to Maturity - Amortized Cost	501,949,000	525,258,000
Held To Maturity Securities, Continuous Unrealized Loss Position Aggregate Losses [Abstract]
Held to Maturity- Unrealized Loss - less than 12 month	7,152,000	7,266,000
Held to Maturity- Unrealized Loss	7,152,000	7,266,000
Held To Maturity Securities Continuous Unrealized Loss Position Fair Value [Abstract]
Held-to-Maturity - Fair Value - less than 12 Month	494,797,000	517,992,000
Held to Maturity - Fair Value	494,797,000	517,992,000
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	30,727,000	29,445,000
Total Available for Sale Amortization cost	30,727,000	29,445,000
Available For Sale Securities Continuous Unrealized Loss Position Aggregate Losses [Abstract]
Available for sale - Unrealized Loss - less than 12 month	727,000	620,000
Total Available for Sale Unrealized Loss	727,000	620,000
Available For Sale Securities Continuous Unrealized Loss Position Fair Value [Abstract]
Available for sale - Fair Value - less than 12 month	30,000,000	28,825,000
Total Available for Sale Fair Value	30,000,000	28,825,000
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 - less than 12 month	3,604,000	3,903,000
Total Available for Sale Amortization cost	3,604,000	3,903,000
Available For Sale Securities Continuous Unrealized Loss Position Aggregate Losses [Abstract]
Available for sale - Unrealized Loss - less than 12 month	19,000	618,000
Total Available for Sale Unrealized Loss	19,000	618,000
Available For Sale Securities Continuous Unrealized Loss Position Fair Value [Abstract]
Available for sale - Fair Value - less than 12 month	3,585,000	3,884,000
Total Available for Sale Fair Value	3,585,000	3,884,000
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	49,206,000	49,172,000
Total Available for Sale Amortization cost	49,206,000	49,172,000
Available For Sale Securities Continuous Unrealized Loss Position Aggregate Losses [Abstract]
Available for sale - Unrealized Loss - less than 12 month	526,000	618,000
Total Available for Sale Unrealized Loss	526,000	618,000
Available For Sale Securities Continuous Unrealized Loss Position Fair Value [Abstract]
Available for sale - Fair Value - less than 12 month	48,680,000	48,554,000
Total Available for Sale Fair Value	$ 48,680,000	$ 48,554,000

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Amount of unrealized loss on investments in available-for-sale securities that have been in a loss position for less than twelve months.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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