Fair Value Measurements (Assets And Liabilities Measured On Recurring Basis) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Restricted cash and cash equivalents	$ 8,150	$ 6,291
Gain included in interest and other income/expense	1,400
Equity securities, unrealized loss	(3,000)
Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	97,733	40,738
Deferred compensation plan obligations	30,996	31,497
Total	30,996	31,497
Recurring [Member] | Quoted Prices In Active Markets For Identical Assets And Liabilities (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	97,733	38,703
Deferred compensation plan obligations	30,996	31,497
Total	30,996	31,497
Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	0	2,035
Total	0	0
Recurring [Member] | Fair Value Using Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total	0	0
Total	0	0
Money Market Funds [Member] | Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents, fair value disclosure	54,848
Restricted cash and cash equivalents	5,254
Money Market Funds [Member] | Recurring [Member] | Quoted Prices In Active Markets For Identical Assets And Liabilities (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents, fair value disclosure	54,848
Restricted cash and cash equivalents	5,254
Grantor Trusts [Member] | Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	30,996	31,497
Grantor Trusts [Member] | Recurring [Member] | Quoted Prices In Active Markets For Identical Assets And Liabilities (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	30,996	31,497
Equity Funds [Member] | Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	6,635	7,206
Equity Funds [Member] | Recurring [Member] | Quoted Prices In Active Markets For Identical Assets And Liabilities (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	$ 6,635	7,206
Interest Rate Contracts [Member] | Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		2,035
Interest Rate Contracts [Member] | Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets		$ 2,035