Employee Benefit Plans (Schedule of Defined Benefit Plan Amounts Recognized in Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Tax benefit (expense)	$ (622)	$ (1,284)	$ 4,192
Total other comprehensive income (loss)	(247,590)	779,705	211,358
Net Actuarial Pension Loss [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial gain (loss)	0	3,728	(25,243)
Amortization of net actuarial loss	2,963	3,815	1,951
Tax benefit (expense)	(622)	(1,284)	4,192
Total other comprehensive income (loss)	$ 2,341	$ 6,259	$ (19,100)