Fair Value of Financial Instruments (Financial Assets Measured at Fair Value on Nonrecurring Basis (Details) - Nonrecurring [Member] - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	$ 184,205	$ 169,888
Other real estate owned	6,928	13,968
Total nonrecurring fair value measurements	191,133	183,856
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Collateral dependent impaired loans	184,205	169,888
Total nonrecurring fair value measurements	184,205	169,888
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other real estate owned	6,928	13,968
Total nonrecurring fair value measurements	$ 6,928	$ 13,968