Loans and Allowance for Credit Losses - Loan Classification by Risk Rating Category (Details) - USD ($) $ in Thousands		Mar. 31, 2021	Dec. 31, 2020
Financing Receivable, Credit Quality Indicator [Line Items]
2021		$ 2,776,700
2020		7,314,277
2019		3,992,488
2018		2,215,245
2017		1,293,225
Prior		1,964,579
Revolving Loans		3,530,187
Total		23,086,701	$ 22,424,501
Potential problem loans not included in nonperforming assets		160,800	173,500
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2021		2,761,358
2020		6,643,781
2019		3,735,521
2018		2,115,454
2017		1,152,995
Prior		1,808,130
Revolving Loans		3,468,908
Total		21,686,147
Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
2021		8,600
2020		593,082
2019		224,401
2018		72,300
2017		121,247
Prior		117,274
Revolving Loans		30,689
Total		1,167,593
Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2021	[1]	5,463
2020	[1]	51,266
2019	[1]	23,536
2018	[1]	22,634
2017	[1]	16,366
Prior	[1]	19,894
Revolving Loans	[1]	21,667
Total	[1]	160,826
Substandard-nonaccrual
Financing Receivable, Credit Quality Indicator [Line Items]
2021		1,279
2020		26,148
2019		9,030
2018		4,857
2017		2,617
Prior		19,281
Revolving Loans		8,923
Total		72,135
Doubtful-nonaccrual
Financing Receivable, Credit Quality Indicator [Line Items]
2021		0
2020		0
2019		0
2018		0
2017		0
Prior		0
Revolving Loans		0
Total		0
Commercial real estate - Owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
2021		186,342
2020		860,251
2019		484,369
2018		444,564
2017		310,594
Prior		503,750
Revolving Loans		79,915
Total		2,869,785	2,802,227
Commercial real estate - Owner occupied | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2021		185,030
2020		818,913
2019		454,195
2018		415,769
2017		287,792
Prior		482,233
Revolving Loans		75,410
Total		2,719,342
Commercial real estate - Owner occupied | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
2021		843
2020		21,745
2019		23,153
2018		18,193
2017		9,943
Prior		7,773
Revolving Loans		100
Total		81,750
Commercial real estate - Owner occupied | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2021	[1]	0
2020	[1]	15,418
2019	[1]	6,878
2018	[1]	7,720
2017	[1]	12,034
Prior	[1]	9,215
Revolving Loans	[1]	4,405
Total	[1]	55,670
Commercial real estate - Owner occupied | Substandard-nonaccrual
Financing Receivable, Credit Quality Indicator [Line Items]
2021		469
2020		4,175
2019		143
2018		2,882
2017		825
Prior		4,529
Revolving Loans		0
Total		13,023
Commercial real estate - Owner occupied | Doubtful-nonaccrual
Financing Receivable, Credit Quality Indicator [Line Items]
2021		0
2020		0
2019		0
2018		0
2017		0
Prior		0
Revolving Loans		0
Total		0
Commercial real estate - Non-owner occupied
Financing Receivable, Credit Quality Indicator [Line Items]
2021		371,805
2020		1,707,370
2019		1,278,098
2018		709,072
2017		566,825
Prior		863,499
Revolving Loans		76,512
Total		5,573,181	5,203,384
Commercial real estate - Non-owner occupied | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2021		363,560
2020		1,195,970
2019		1,148,016
2018		655,692
2017		460,511
Prior		753,838
Revolving Loans		76,477
Total		4,654,064
Commercial real estate - Non-owner occupied | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
2021		4,790
2020		499,220
2019		128,032
2018		49,715
2017		104,627
Prior		101,186
Revolving Loans		35
Total		887,605
Commercial real estate - Non-owner occupied | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2021	[1]	3,364
2020	[1]	12,177
2019	[1]	1,634
2018	[1]	3,092
2017	[1]	1,687
Prior	[1]	6,099
Revolving Loans		0
Total	[1]	28,053
Commercial real estate - Non-owner occupied | Substandard-nonaccrual
Financing Receivable, Credit Quality Indicator [Line Items]
2021		91
2020		3
2019		416
2018		573
2017		0
Prior		2,376
Revolving Loans		0
Total		3,459
Commercial real estate - Non-owner occupied | Doubtful-nonaccrual
Financing Receivable, Credit Quality Indicator [Line Items]
2021		0
2020		0
2019		0
2018		0
2017		0
Prior		0
Revolving Loans		0
Total		0
Consumer real estate – mortgage
Financing Receivable, Credit Quality Indicator [Line Items]
2021		208,214
2020		704,468
2019		436,261
2018		279,820
2017		147,980
Prior		388,469
Revolving Loans		921,704
Total		3,086,916	3,099,172
Consumer real estate – mortgage | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2021		208,011
2020		703,564
2019		432,848
2018		278,303
2017		146,508
Prior		374,293
Revolving Loans		917,280
Total		3,060,807
Consumer real estate – mortgage | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
2021		121
2020		0
2019		0
2018		710
2017		66
Prior		957
Revolving Loans		0
Total		1,854
Consumer real estate – mortgage | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2021		0
2020	[1]	661
2019		0
2018	[1]	0
2017	[1]	183
Prior	[1]	1,872
Revolving Loans	[1]	1,760
Total	[1]	4,476
Consumer real estate – mortgage | Substandard-nonaccrual
Financing Receivable, Credit Quality Indicator [Line Items]
2021		82
2020		243
2019		3,413
2018		807
2017		1,223
Prior		11,347
Revolving Loans		2,664
Total		19,779
Consumer real estate – mortgage | Doubtful-nonaccrual
Financing Receivable, Credit Quality Indicator [Line Items]
2021		0
2020		0
2019		0
2018		0
2017		0
Prior		0
Revolving Loans		0
Total		0
Construction and land development
Financing Receivable, Credit Quality Indicator [Line Items]
2021		232,072
2020		1,166,992
2019		826,244
2018		275,582
2017		32,215
Prior		24,450
Revolving Loans		11,414
Total		2,568,969	2,901,746
Construction and land development | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2021		230,571
2020		1,127,479
2019		817,068
2018		275,489
2017		32,141
Prior		19,315
Revolving Loans		11,414
Total		2,513,477
Construction and land development | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
2021		1,501
2020		38,796
2019		8,638
2018		0
2017		0
Prior		4,243
Revolving Loans		0
Total		53,178
Construction and land development | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2021		0
2020	[1]	354
2019	[1]	14
2018	[1]	25
2017		0
Prior	[1]	363
Revolving Loans		0
Total	[1]	756
Construction and land development | Substandard-nonaccrual
Financing Receivable, Credit Quality Indicator [Line Items]
2021		0
2020		363
2019		524
2018		68
2017		74
Prior		529
Revolving Loans		0
Total		1,558
Construction and land development | Doubtful-nonaccrual
Financing Receivable, Credit Quality Indicator [Line Items]
2021		0
2020		0
2019		0
2018		0
2017		0
Prior		0
Revolving Loans		0
Total		0
Commercial and industrial
Financing Receivable, Credit Quality Indicator [Line Items]
2021		1,685,064
2020		2,754,648
2019		953,621
2018		501,142
2017		230,133
Prior		180,244
Revolving Loans		2,271,676
Total		8,576,528	8,038,457
Commercial and industrial | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2021		1,680,983
2020		2,677,307
2019		869,499
2018		485,136
2017		220,590
Prior		174,287
Revolving Loans		2,219,361
Total		8,327,163
Commercial and industrial | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
2021		1,345
2020		33,321
2019		64,578
2018		3,682
2017		6,611
Prior		3,115
Revolving Loans		30,554
Total		143,206
Commercial and industrial | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2021	[1]	2,099
2020	[1]	22,656
2019	[1]	15,010
2018	[1]	11,797
2017	[1]	2,462
Prior	[1]	2,345
Revolving Loans	[1]	15,502
Total	[1]	71,871
Commercial and industrial | Substandard-nonaccrual
Financing Receivable, Credit Quality Indicator [Line Items]
2021		637
2020		21,364
2019		4,534
2018		527
2017		470
Prior		497
Revolving Loans		6,259
Total		34,288
Commercial and industrial | Doubtful-nonaccrual
Financing Receivable, Credit Quality Indicator [Line Items]
2021		0
2020		0
2019		0
2018		0
2017		0
Prior		0
Revolving Loans		0
Total		0
Consumer and other
Financing Receivable, Credit Quality Indicator [Line Items]
2021		93,203
2020		120,548
2019		13,895
2018		5,065
2017		5,478
Prior		4,167
Revolving Loans		168,966
Total		411,322	$ 379,515
Consumer and other | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2021		93,203
2020		120,548
2019		13,895
2018		5,065
2017		5,453
Prior		4,164
Revolving Loans		168,966
Total		411,294
Consumer and other | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
2021		0
2020		0
2019		0
2018		0
2017		0
Prior		0
Revolving Loans		0
Total		0
Consumer and other | Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2021		0
2020		0
2019		0
2018		0
2017		0
Prior		0
Revolving Loans		0
Total	[1]	0
Consumer and other | Substandard-nonaccrual
Financing Receivable, Credit Quality Indicator [Line Items]
2021		0
2020		0
2019		0
2018		0
2017		25
Prior		3
Revolving Loans		0
Total		28
Consumer and other | Doubtful-nonaccrual
Financing Receivable, Credit Quality Indicator [Line Items]
2021		0
2020		0
2019		0
2018		0
2017		0
Prior		0
Revolving Loans		0
Total		$ 0

[1] Potential problem loans represent those loans with a well-defined weakness and where information about possible credit problems of borrowers has caused management to have doubts about the borrower's ability to comply with present repayment terms. This definition is believed to be substantially consistent with the standards established by Pinnacle Bank's primary regulators for loans classified as substandard, excluding troubled debt restructurings. Potential problem loans, which are not included in nonaccrual loans, amounted to approximately $160.8 million at March 31, 2021, compared to $173.5 million at December 31, 2020.