Consolidated Balance Sheets Parentheticals - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Investment securities available for sale at amortized cost	$ 1,197,171	$ 1,283,161
Investment securities held to maturity at fair value	$ 98,713	$ 92,604
Preferred Stock, Par or Stated Value Per Share	$ 1.00	$ 1.00
Preferred Stock, Shares Authorized	2,000,000	2,000,000
Common Stock, Par or Stated Value Per Share	$ 1.00	$ 1.00
Common Stock, Shares Authorized	170,000,000	170,000,000
Common Stock, Shares, Issued	84,134,104	83,731,769
Common Stock, Shares, Outstanding	84,134,104	83,731,769
Series D Preferred Stock [Member]
Preferred Stock, Shares Issued	50,000	50,000
Preferred Stock, Shares Outstanding	50,000	50,000
Preferred Stock, Liquidation Preference Per Share	$ 1,000	$ 1,000