Fair Value Measurements (Assets And Liabilities Measured At Fair Value On Recurring Basis) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 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	$ 309,267	$ 202,197
Restricted cash	4,485	9,199
Restricted investments	84,498	84,355
Investments in lieu of retainage	78,512	86,328
Total	476,762	382,079
Fair value measured on a recurring basis | Level 1
Assets:
Cash and cash equivalents	309,267	202,197
Restricted cash	4,485	9,199
Restricted investments	0	0
Investments in lieu of retainage	16,102	27,472
Total	329,854	238,868
Fair value measured on a recurring basis | Level 2
Assets:
Cash and cash equivalents	0	0
Restricted cash	0	0
Restricted investments	84,498	84,355
Investments in lieu of retainage	62,410	58,856
Total	146,908	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	16,100	27,500
Debt Securities | Fair value measured on a recurring basis | Level 1
Assets:
Investments in lieu of retainage	$ 62,400	$ 58,900