Employee Benefit Plans (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Contribution Plan, Cost Recognized	$ 7,400	$ 5,000	$ 3,800
Deferred Compensation Liability, Current and Noncurrent	$ 4,900	3,900
Salary continuation plan minimum period	10 years
Salary continuation plan maximum period	20 years
Present Value Of Future Salary Contribution Plan Benefits	$ 36,100	42,300
Postemployment Benefits, Period Expense	1,100	2,900	849
Deferred Compensation Cash-based Arrangements, Liability, Current and Noncurrent	9,600	9,100
Cash Surrender Value of Life Insurance	291,900	294,300
Other Postretirement Defined Benefit Plan, Liabilities	6,200	6,200
Supplemental Employee Retirement Plans, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Contributions by Employer	178	140	$ 123
Other Deferred Compensation Arrangements, Liability, Current and Noncurrent	$ 889	812
Percentage Of Deferred Salary	50.00%
Pension and Other Postretirement Defined Benefit Plans, Liabilities	$ 8,700	$ 8,700