Summary of Significant Accounting Policies (Correction of an Immaterial Error to the Financial Statements (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Decrease in loans held-for-sale	$ (231,464)	$ (187,117)
Decrease in proceeds from sales of loans held for sale	(238,137)	(152,185)
Decrease in net change in other assets and liabilities	(37,405)	(14,297)
Decrease in net cash provided by operating activities	146,368	123,137
Loans and Leases	9,573,956	8,694,097	$ 8,949,785
Proceeds from Sales of Loans	137,717	118,089
Increase to net cash used in investing activities	(875,040)	(643,909)
Decrease in transfers from loans to loans held for sale	86,625	$ 140,439
Adjustment For Error Correction, YTD 2016 | Immaterial Error From Amounts Incorrectly Reported In Prior Period
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Decrease in loans held-for-sale	136,700
Decrease in proceeds from sales of loans held for sale	116,600
Decrease in net change in other assets and liabilities	100
Decrease in net cash provided by operating activities	20,100
Loans and Leases	138,200
Proceeds from Sales of Loans	118,100
Increase to net cash used in investing activities	20,100
Decrease in transfers from loans to loans held for sale	$ (3,500)