Portfolio Loans - Summary of risk grades segregated by category (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Loans
Portfolio loans	$ 7,188,998	$ 6,814,177
Pass
Loans
Portfolio loans	6,518,101	6,016,748
Watch
Loans
Portfolio loans	463,053	554,970
Special Mention
Loans
Portfolio loans	121,120	150,481
Substandard
Loans
Portfolio loans	70,778	69,048
Substandard Non-accrual
Loans
Portfolio loans	15,946	22,930
Commercial
Loans
Portfolio loans	1,943,886	2,014,576
Commercial | Pass
Loans
Portfolio loans	1,747,756	1,768,755
Commercial | Watch
Loans
Portfolio loans	93,582	136,948
Commercial | Special Mention
Loans
Portfolio loans	69,427	72,447
Commercial | Substandard
Loans
Portfolio loans	26,117	27,903
Commercial | Substandard Non-accrual
Loans
Portfolio loans	7,004	8,523
Commercial real estate
Loans
Portfolio loans	3,119,807	2,892,535
Commercial real estate | Pass
Loans
Portfolio loans	2,682,441	2,393,372
Commercial real estate | Watch
Loans
Portfolio loans	343,304	383,277
Commercial real estate | Special Mention
Loans
Portfolio loans	49,695	75,486
Commercial real estate | Substandard
Loans
Portfolio loans	38,394	34,897
Commercial real estate | Substandard Non-accrual
Loans
Portfolio loans	5,973	5,503
Real estate construction
Loans
Portfolio loans	385,996	461,786
Real estate construction | Pass
Loans
Portfolio loans	369,797	434,681
Real estate construction | Watch
Loans
Portfolio loans	13,793	24,481
Real estate construction | Special Mention
Loans
Portfolio loans	6	77
Real estate construction | Substandard
Loans
Portfolio loans	2,400	2,546
Real estate construction | Substandard Non-accrual
Loans
Portfolio loans		1
Retail real estate
Loans
Portfolio loans	1,512,976	1,407,852
Retail real estate | Pass
Loans
Portfolio loans	1,491,845	1,382,616
Retail real estate | Watch
Loans
Portfolio loans	12,374	10,264
Retail real estate | Special Mention
Loans
Portfolio loans	1,992	2,471
Retail real estate | Substandard
Loans
Portfolio loans	3,867	3,702
Retail real estate | Substandard Non-accrual
Loans
Portfolio loans	2,898	8,799
Retail other
Loans
Portfolio loans	226,333	37,428
Retail other | Pass
Loans
Portfolio loans	226,262	37,324
Retail other | Substandard Non-accrual
Loans
Portfolio loans	71	104
Commercial Loans
Loans
Portfolio loans	1,943,886	2,014,576
Commercial Real Estate Loans
Loans
Portfolio loans	3,119,807	2,892,535
Real Estate Construction
Loans
Portfolio loans	385,996	461,786
Retail real estate
Loans
Portfolio loans	1,512,976	1,407,852
Retail other
Loans
Portfolio loans	$ 226,333	$ 37,428