Loans and Leases and the Allowance for Loan and Lease Losses (Allowance for Loan and Lease Losses) (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Allowance for Loan and Lease Losses:
Balance at the Beginning of Period	$ 106,693	$ 107,346	$ 104,273
Loans and Leases Charged-Off	(23,955)	(24,564)	(23,255)
Recoveries on Loans and Leases Previously Charged-Off	11,289	10,486	9,428
Net Loans and Leases Recovered (Charged-Off)	(12,666)	(14,078)	(13,827)
Provision for Credit Losses	16,000	13,425	16,900
Balance at End of Period	110,027	106,693	107,346
Allowance for Loan and Lease Losses:
Individually Evaluated for Impairment				$ 5,903	$ 3,976	$ 3,916
Collectively Evaluated for Impairment				104,124	102,717	103,430
Total	110,027	107,346	107,346	110,027	106,693	107,346
Recorded Investment in Loans and Leases:
Individually Evaluated for Impairment				75,202	54,625	61,218
Collectively Evaluated for Impairment				10,915,690	10,394,149	9,735,729
Total Loans and Leases				10,990,892	10,448,774	9,796,947
Commercial
Allowance for Loan and Lease Losses:
Balance at the Beginning of Period	66,874	65,822	65,680
Loans and Leases Charged-Off	(2,738)	(1,505)	(1,408)
Recoveries on Loans and Leases Previously Charged-Off	1,513	2,039	1,485
Net Loans and Leases Recovered (Charged-Off)	(1,225)	534	77
Provision for Credit Losses	8,152	518	65
Balance at End of Period	73,801	66,874	65,822
Allowance for Loan and Lease Losses:
Individually Evaluated for Impairment				2,657	222	141
Collectively Evaluated for Impairment				71,144	66,652	65,681
Total	66,874	66,874	65,680	73,801	66,874	65,822
Recorded Investment in Loans and Leases:
Individually Evaluated for Impairment				35,442	12,298	20,216
Collectively Evaluated for Impairment				4,178,385	3,967,494	3,746,282
Total Loans and Leases				4,213,827	3,979,792	3,766,498
Consumer
Allowance for Loan and Lease Losses:
Balance at the Beginning of Period	39,819	41,524	38,593
Loans and Leases Charged-Off	(21,217)	(23,059)	(21,847)
Recoveries on Loans and Leases Previously Charged-Off	9,776	8,447	7,943
Net Loans and Leases Recovered (Charged-Off)	(11,441)	(14,612)	(13,904)
Provision for Credit Losses	7,848	12,907	16,835
Balance at End of Period	36,226	39,819	41,524
Allowance for Loan and Lease Losses:
Individually Evaluated for Impairment				3,246	3,754	3,775
Collectively Evaluated for Impairment				32,980	36,065	37,749
Total	$ 36,226	$ 41,524	$ 41,524	36,226	39,819	41,524
Recorded Investment in Loans and Leases:
Individually Evaluated for Impairment				39,760	42,327	41,002
Collectively Evaluated for Impairment				6,737,305	6,426,655	5,989,447
Total Loans and Leases				$ 6,777,065	$ 6,468,982	$ 6,030,449