Fair Value Measurements (Details 6) - Fair Value, Measurements, Nonrecurring - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	$ 46,510	$ 544,658
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	44,429	55,952
Non Purchased Credit Impaired Loans and Leases
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	45,557	61,095
Non Purchased Credit Impaired Loans and Leases | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	44,429	$ 55,952
Discount Rates | Discounted Cash Flow | Non Purchased Credit Impaired Loans and Leases | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	32,638
No Discounts | Third party appraisals | Non Purchased Credit Impaired Loans and Leases | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans	$ 11,791
Minimum | Discounted Cash Flow | Non Purchased Credit Impaired Loans and Leases | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rates	2.00%
Maximum | Discounted Cash Flow | Non Purchased Credit Impaired Loans and Leases | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rates	10.20%
Weighted Average | Discounted Cash Flow | Non Purchased Credit Impaired Loans and Leases | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rates	7.33%
Weighted Average | Discount Rates | Discounted Cash Flow | Non Purchased Credit Impaired Loans and Leases | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount rates	7.33%