Allowance for Credit Losses (Non-PCI Impaired Loans and Leases) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2019
Financing Receivable, Allowance for Credit Loss [Line Items]
Non-PCI impaired loans collective maximum balance collectively evaluated for impairment		$ 500,000
Impaired financing receivable, collectively evaluated		41,000,000.0
Non-PCD Loans
Financing Receivable, Allowance for Credit Loss [Line Items]
With a recorded allowance		133,358,000
With no recorded allowance		52,241,000
Loans and leases individually evaluated for impairment		185,599,000
Unpaid principal balance		200,599,000
Related allowance recorded		12,915,000
Average balance	$ 147,891,000
Interest income recognized	1,339,000
Non-PCD Loans | Commercial
Financing Receivable, Allowance for Credit Loss [Line Items]
With a recorded allowance		52,516,000
With no recorded allowance		36,377,000
Loans and leases individually evaluated for impairment		88,893,000
Unpaid principal balance		95,927,000
Related allowance recorded		5,634,000
Average balance	69,776,000
Interest income recognized	702,000
Non-PCD Loans | Noncommercial
Financing Receivable, Allowance for Credit Loss [Line Items]
With a recorded allowance		80,842,000
With no recorded allowance		15,864,000
Loans and leases individually evaluated for impairment		96,706,000
Unpaid principal balance		104,672,000
Related allowance recorded		7,281,000
Average balance	78,115,000
Interest income recognized	637,000
Construction and land development | Non-PCD Loans | Commercial
Financing Receivable, Allowance for Credit Loss [Line Items]
With a recorded allowance		1,851,000
With no recorded allowance		2,804,000
Loans and leases individually evaluated for impairment		4,655,000
Unpaid principal balance		5,109,000
Related allowance recorded		463,000
Average balance	2,147,000
Interest income recognized	28,000
Construction and land development | Non-PCD Loans | Noncommercial
Financing Receivable, Allowance for Credit Loss [Line Items]
With a recorded allowance		2,470,000
With no recorded allowance		1,412,000
Loans and leases individually evaluated for impairment		3,882,000
Unpaid principal balance		4,150,000
Related allowance recorded		174,000
Average balance	3,747,000
Interest income recognized	36,000
Mortgage | Non-PCD Loans | Commercial
Financing Receivable, Allowance for Credit Loss [Line Items]
With a recorded allowance		42,394,000
With no recorded allowance		27,755,000
Loans and leases individually evaluated for impairment		70,149,000
Unpaid principal balance		74,804,000
Related allowance recorded		3,650,000
Average balance	56,629,000
Interest income recognized	564,000
Mortgage | Non-PCD Loans | Noncommercial
Financing Receivable, Allowance for Credit Loss [Line Items]
With a recorded allowance		48,796,000
With no recorded allowance		11,646,000
Loans and leases individually evaluated for impairment		60,442,000
Unpaid principal balance		64,741,000
Related allowance recorded		3,278,000
Average balance	42,626,000
Interest income recognized	325,000
Revolving mortgage | Non-PCD Loans | Noncommercial
Financing Receivable, Allowance for Credit Loss [Line Items]
With a recorded allowance		26,104,000
With no recorded allowance		2,765,000
Loans and leases individually evaluated for impairment		28,869,000
Unpaid principal balance		31,960,000
Related allowance recorded		2,722,000
Average balance	28,742,000
Interest income recognized	247,000
Consumer | Non-PCD Loans | Noncommercial
Financing Receivable, Allowance for Credit Loss [Line Items]
With a recorded allowance		3,472,000
With no recorded allowance		41,000
Loans and leases individually evaluated for impairment		3,513,000
Unpaid principal balance		3,821,000
Related allowance recorded		1,107,000
Average balance	3,000,000
Interest income recognized	29,000
Other | Non-PCD Loans | Commercial
Financing Receivable, Allowance for Credit Loss [Line Items]
With a recorded allowance		406,000
With no recorded allowance		233,000
Loans and leases individually evaluated for impairment		639,000
Unpaid principal balance		661,000
Related allowance recorded		103,000
Average balance	315,000
Interest income recognized	2,000
Other commercial real estate | Non-PCD Loans | Commercial
Financing Receivable, Allowance for Credit Loss [Line Items]
With a recorded allowance		318,000
With no recorded allowance		950,000
Loans and leases individually evaluated for impairment		1,268,000
Unpaid principal balance		1,360,000
Related allowance recorded		39,000
Average balance	685,000
Interest income recognized	8,000
Commercial and industrial and leases | Non-PCD Loans | Commercial
Financing Receivable, Allowance for Credit Loss [Line Items]
With a recorded allowance		7,547,000
With no recorded allowance		4,635,000
Loans and leases individually evaluated for impairment		12,182,000
Unpaid principal balance		13,993,000
Related allowance recorded		$ 1,379,000
Average balance	10,000,000
Interest income recognized	$ 100,000