Employee Benefit Plans (Fair Value and Allocation Of Plan Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 976,072	$ 842,534	$ 881,590
Actual % of Plan Assets	100.00%	100.00%
Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs)
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 775,527	$ 620,658
Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs)
Defined Benefit Plan Disclosure [Line Items]
Plan assets	200,545	221,876
Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0	0
Cash and equivalents
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 10,974	$ 19,029
Actual % of Plan Assets	1.00%	2.00%
Cash and equivalents | Minimum
Defined Benefit Plan Disclosure [Line Items]
Target Allocation		0.00%
Cash and equivalents | Maximum
Defined Benefit Plan Disclosure [Line Items]
Target Allocation		5.00%
Cash and equivalents | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs)
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 10,974	$ 19,029
Cash and equivalents | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs)
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0	0
Cash and equivalents | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0	0
Equity securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 142,157	$ 143,939
Actual % of Plan Assets	73.00%	64.00%
Equity securities | Minimum
Defined Benefit Plan Disclosure [Line Items]
Target Allocation		30.00%
Equity securities | Maximum
Defined Benefit Plan Disclosure [Line Items]
Target Allocation		70.00%
Equity securities | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs)
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 142,157	$ 143,939
Equity securities | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs)
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0	0
Equity securities | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0	0
Equity mutual funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets	565,343	395,328
Equity mutual funds | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs)
Defined Benefit Plan Disclosure [Line Items]
Plan assets	565,343	393,104
Equity mutual funds | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs)
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0	2,224
Equity mutual funds | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 0	$ 0
Debt Securities
Defined Benefit Plan Disclosure [Line Items]
Actual % of Plan Assets	23.00%	30.00%
Debt Securities | Minimum
Defined Benefit Plan Disclosure [Line Items]
Target Allocation		15.00%
Debt Securities | Maximum
Defined Benefit Plan Disclosure [Line Items]
Target Allocation		45.00%
US government and government agency securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 78,175	$ 79,294
US government and government agency securities | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs)
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0	0
US government and government agency securities | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs)
Defined Benefit Plan Disclosure [Line Items]
Plan assets	78,175	79,294
US government and government agency securities | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0	0
Corporate Bonds
Defined Benefit Plan Disclosure [Line Items]
Plan assets	122,370	140,358
Corporate Bonds | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs)
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0	0
Corporate Bonds | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs)
Defined Benefit Plan Disclosure [Line Items]
Plan assets	122,370	140,358
Corporate Bonds | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0	0
Fixed Income Mutual Funds
Defined Benefit Plan Disclosure [Line Items]
Plan assets	25,288	29,561
Fixed Income Mutual Funds | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs)
Defined Benefit Plan Disclosure [Line Items]
Plan assets	25,288	29,561
Fixed Income Mutual Funds | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs)
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0	0
Fixed Income Mutual Funds | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0	0
Alternative investments
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 31,765	$ 35,025
Actual % of Plan Assets	3.00%	4.00%
Alternative investments | Minimum
Defined Benefit Plan Disclosure [Line Items]
Target Allocation		0.00%
Alternative investments | Maximum
Defined Benefit Plan Disclosure [Line Items]
Target Allocation		30.00%
Alternative investments | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1 Inputs)
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 31,765	$ 35,025
Alternative investments | Quoted Prices for Similar Assets and Liabilities (Level 2 Inputs)
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0	0
Alternative investments | Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 0	$ 0