Investment Securities (Unrealized Gains and Losses by Category) (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Available For Sale Securities Continuous Unrealized Loss Position Amortized Cost [Abstract]
Available for sale - Amortized cost - less than 12 month	$ 20	$ 127,221
Available for sale - Amortized cost - more than 12 month	556,515	567,531
Total Available for Sale Amortization cost	556,535	694,752
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available for sale - Unrealized Loss - less than 12 month	1	436
Available for sale - Unrealized Loss - more than 12 month	6,014	13,687
Total Available for Sale Unrealized Loss	6,015	14,123
Available For Sale Securities Continuous Unrealized Loss Position Fair Value [Abstract]
Available for sale - Fair Value - less than 12 month	19	126,785
Available-for-sale, Fair Value - more than 12 month	550,501	553,844
Total Available for Sale Fair Value	550,520	680,629
Continuous Unrealized Loss Position Amortized Cost [Abstract]
Held to Maturity - Amortized cost - more than 12 month		424,740
Held to Maturity - Amortized Cost		424,740
Held To Maturity Securities, Continuous Unrealized Loss Position Aggregate Losses [Abstract]
Held to Maturity- Unrealized Loss - more than 12 month		14,387
Held to Maturity- Unrealized Loss		14,387
Held To Maturity Securities Continuous Unrealized Loss Position Fair Value [Abstract]
Held-to-Maturity - Fair Value - more than 12 Month		410,353
Held to Maturity - Fair Value		410,353
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 - more than 12 month	59,238	66,230
Total Available for Sale Amortization cost	59,238	66,230
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available for sale - Unrealized Loss - more than 12 month	608	2,166
Total Available for Sale Unrealized Loss	608	2,166
Available For Sale Securities Continuous Unrealized Loss Position Fair Value [Abstract]
Available-for-sale, Fair Value - more than 12 month	58,630	64,064
Total Available for Sale Fair Value	58,630	64,064
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
Available for sale - Amortized cost - more than 12 month	480,959	357,955
Total Available for Sale Amortization cost	480,959	467,727
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available for sale - Unrealized Loss - less than 12 month		348
Available for sale - Unrealized Loss - more than 12 month	5,352	8,603
Total Available for Sale Unrealized Loss	5,352	8,951
Available For Sale Securities Continuous Unrealized Loss Position Fair Value [Abstract]
Available for sale - Fair Value - less than 12 month		109,424
Available-for-sale, Fair Value - more than 12 month	475,607	349,352
Total Available for Sale Fair Value	475,607	458,776
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	20	17,126
Available for sale - Amortized cost - more than 12 month	4,181	131,044
Total Available for Sale Amortization cost	4,201	148,170
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available for sale - Unrealized Loss - less than 12 month	1	88
Available for sale - Unrealized Loss - more than 12 month	6	2,739
Total Available for Sale Unrealized Loss	7	2,827
Available For Sale Securities Continuous Unrealized Loss Position Fair Value [Abstract]
Available for sale - Fair Value - less than 12 month	19	17,038
Available-for-sale, Fair Value - more than 12 month	4,175	128,305
Total Available for Sale Fair Value	4,194	145,343
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	2,147	2,325
Total Available for Sale Amortization cost	2,147	2,325
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available for sale - Unrealized Loss - more than 12 month	16	60
Total Available for Sale Unrealized Loss	16	60
Available For Sale Securities Continuous Unrealized Loss Position Fair Value [Abstract]
Available-for-sale, Fair Value - more than 12 month	2,131	2,265
Total Available for Sale Fair Value	2,131	2,265
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
Available for sale - Amortized cost - more than 12 month	9,990	9,977
Total Available for Sale Amortization cost	9,990	10,300
Available-for-sale Securities, Continuous Unrealized Loss Position [Abstract]
Available for sale - Unrealized Loss - less than 12 month		0
Available for sale - Unrealized Loss - more than 12 month	32	119
Total Available for Sale Unrealized Loss	32	119
Available For Sale Securities Continuous Unrealized Loss Position Fair Value [Abstract]
Available for sale - Fair Value - less than 12 month		323
Available-for-sale, Fair Value - more than 12 month	9,958	9,858
Total Available for Sale Fair Value	$ 9,958	$ 10,181

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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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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Amount of unrealized loss on securities classified as available-for-sale.

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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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This item represents the aggregate fair value of investments in debt and equity securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for less than twelve months.

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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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
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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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Fair value of investment in debt security measured at amortized cost (held-to-maturity), in continuous unrealized loss position for 12 months or longer.

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