Fair Value Measurements (Assets And Liabilities Measured At Fair Value On Recurring Basis) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Dec. 31, 2022
Assets:
Cash and cash equivalents maturity period (maximum)	3 months
Fair value measured on a recurring basis
Assets:
Cash and cash equivalents	$ 282,695	$ 259,351
Restricted cash	19,946	14,480
Restricted investments	88,240	91,556
Investments in lieu of retainage	90,476	88,328
Total	481,357	453,715
Fair value measured on a recurring basis | Level 1
Assets:
Cash and cash equivalents	282,695	259,351
Restricted cash	19,946	14,480
Restricted investments	0	0
Investments in lieu of retainage	23,177	20,100
Total	325,818	293,931
Fair value measured on a recurring basis | Level 2
Assets:
Cash and cash equivalents	0	0
Restricted cash	0	0
Restricted investments	88,240	91,556
Investments in lieu of retainage	67,299	68,228
Total	155,539	159,784
Fair value measured on a recurring basis | Level 3
Assets:
Cash and cash equivalents	0	0
Restricted cash	0	0
Restricted investments	0	0
Investments in lieu of retainage	0	0
Total	0	0
Money Market Funds | Fair value measured on a recurring basis | Level 1
Assets:
Investments in lieu of retainage	23,200	20,100
Debt Securities | Fair value measured on a recurring basis | Level 1
Assets:
Investments in lieu of retainage	$ 67,300	$ 68,200