Investment Securities, Securities Available-for-Sale (Details) - USD ($)		Dec. 31, 2020	Dec. 31, 2019
Amortized cost, fair values, and unrealized gains and losses of securities available-for-sale [Abstract]
Amortized cost		$ 789,175,000	$ 502,693,000
Gross unrealized gains		18,716,000	4,905,000
Gross unrealized losses		159,000	212,000
Fair/Book value		807,732,000	507,386,000
US Treasury Notes [Member]
Amortized cost, fair values, and unrealized gains and losses of securities available-for-sale [Abstract]
Amortized cost		14,859,000	54,745,000
Gross unrealized gains		429,000	250,000
Gross unrealized losses		0	0
Fair/Book value		15,288,000	54,995,000
US Government Agency SBA [Member]
Amortized cost, fair values, and unrealized gains and losses of securities available-for-sale [Abstract]
Amortized cost		8,252,000	10,902,000
Gross unrealized gains		1,000	9,000
Gross unrealized losses		93,000	113,000
Fair/Book value		8,160,000	10,798,000
Mortgage Backed Securities [Member]
Amortized cost, fair values, and unrealized gains and losses of securities available-for-sale [Abstract]
Amortized cost	[1]	720,562,000	436,531,000
Gross unrealized gains	[1]	17,359,000	4,646,000
Gross unrealized losses	[1]	48,000	99,000
Fair/Book value	[1]	737,873,000	441,078,000
Corporate Securities [Member]
Amortized cost, fair values, and unrealized gains and losses of securities available-for-sale [Abstract]
Amortized cost		45,010,000
Gross unrealized gains		927,000
Gross unrealized losses		18,000
Fair/Book value		45,919,000
Other [Member]
Amortized cost, fair values, and unrealized gains and losses of securities available-for-sale [Abstract]
Amortized cost		492,000	515,000
Gross unrealized gains		0	0
Gross unrealized losses		0	0
Fair/Book value		$ 492,000	$ 515,000

[1] All Mortgage Backed Securities were issued by an agency or government sponsored entity of the U.S. government.