Summary of Significant Accounting Policies (Correction of Immaterial Errors) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Interest and fees on loans and leases	$ 258,747				$ 229,488
Total interest income	282,259				248,947
Net interest income	237,685				224,981
Net interest income after provision for loan and lease losses	224,001				211,325
Income before provision for income taxes	98,149				103,779
Provision for income taxes	24,116				24,807
Net income	$ 74,033	$ 80,311	$ 90,981	$ 65,999	$ 78,972
Basic (in usd per share)	$ 0.34				$ 0.36
Diluted (in usd per share)	$ 0.34				$ 0.36
Loans and leases	$ 20,405,997	20,422,666			$ 19,255,347
Loans and leases, net	20,261,125	20,277,795
Total assets	27,355,625	26,939,781
Deferred tax liability, net	45,202	25,846
Total liabilities	23,243,299	22,883,339
Retained earnings	629,877	602,482
Total shareholders' equity	4,112,326	4,056,442
Total liabilities and shareholders' equity	27,355,625	$ 26,939,781
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	103,665				46,300
Net cash provided by operating activities	(53,617)				68,990
Net cash used in investing activities	$ 53,539				(236,211)
As Originally Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Interest and fees on loans and leases					227,738
Total interest income					247,197
Net interest income					223,231
Net interest income after provision for loan and lease losses					209,575
Income before provision for income taxes					102,029
Provision for income taxes					24,360
Net income					$ 77,669
Basic (in usd per share)					$ 0.35
Diluted (in usd per share)					$ 0.35
Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Interest and fees on loans and leases					$ 1,750
Total interest income					1,750
Net interest income					1,750
Net interest income after provision for loan and lease losses					1,750
Income before provision for income taxes					1,750
Provision for income taxes					447
Net income					$ 1,303
Basic (in usd per share)					$ 0.01
Diluted (in usd per share)					$ 0.01
Out of Period Correction
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest					$ 1,300
Net cash provided by operating activities					1,800
Net cash used in investing activities					$ (1,800)