Fair Value Measurements (Assets And Liabilities Measured At Fair Value On Recurring Basis) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Dec. 31, 2021
Assets:
Cash and cash equivalents maturity period (maximum)	3 months
Fair value measured on a recurring basis
Assets:
Cash and cash equivalents	$ 323,200	$ 202,197
Restricted cash	21,817	9,199
Restricted investments	79,562	84,355
Investments in lieu of retainage	81,875	86,328
Total	506,454	382,079
Fair value measured on a recurring basis | Level 1
Assets:
Cash and cash equivalents	323,200	202,197
Restricted cash	21,817	9,199
Restricted investments	0	0
Investments in lieu of retainage	23,434	27,472
Total	368,451	238,868
Fair value measured on a recurring basis | Level 2
Assets:
Cash and cash equivalents	0	0
Restricted cash	0	0
Restricted investments	79,562	84,355
Investments in lieu of retainage	58,441	58,856
Total	138,003	143,211
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	23,400	27,500
Debt Securities | Fair value measured on a recurring basis | Level 1
Assets:
Investments in lieu of retainage	$ 58,400	$ 58,900