Other Comprehensive Income (Loss) (Details 2) - USD ($)
$ in Thousands
3 Months Ended 6 Months Ended
Jun. 30, 2016
Jun. 30, 2015
Jun. 30, 2016
Jun. 30, 2015
Tax benefit $ 7,022 $ 9,030 $ 13,989 $ 15,290
Net of tax 14,603 17,422 28,816 30,135
Amount Reclassified from Accumulated Other Comprehensive (Loss) Income [Member] | Available for Sale Securities [Member]        
Net gain on securities transactions [1] 240 723 472 1,013
Tax benefit [1] (96) (289) (189) (405)
Net of tax [1] 144 434 283 608
Amount Reclassified from Accumulated Other Comprehensive (Loss) Income [Member] | Employee Benefit Plans [Member]        
Net retirement plan actuarial loss [1],[2] (326) (729) (669) (1,462)
Net retirement plan prior service credit [1],[2] (8) 190 (38) 369
Amortization, Total before tax [1] (334) (539) (707) (1,093)
Tax benefit [1] 134 214 283 436
Net of tax [1] $ (200) $ (325) $ (424) $ (657)
[1] Amounts in parentheses indicated debits in income statement
[2] The accumulated other comprehensive (loss) income components are included in the computation of net periodic benefit cost (See Note 10 - "Employee Benefit Plan")