Fair Value Measurements (Summarized Information About Level 3 Fair Value Measurements) (Details) - Level 3 - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Convertible Preferred Securities
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Assets, fair value measurement with unobservable input	$ 11,618	$ 8,849	$ 8,404
Recurring | Convertible Preferred Securities | Market approach
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Assets, fair value measurement with unobservable input	11,618	$ 8,849
Nonrecurring | Frac Sand Assets | Third party appraisal
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Assets, fair value measurement with unobservable input	2,946
Nonrecurring | Real Property | Market approach
Fair Value Inputs, Assets, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Assets, fair value measurement with unobservable input	$ 700