Segments (Summary of Assets by Segment and Reconciliation of Segment Assets to Total Assets) (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Reconciliation of total segment assets to total assets
Assets	$ 9,309,069	$ 9,140,332
Operating segments
Reconciliation of total segment assets to total assets
Assets	8,461,876	8,278,491
Operating segments | Operating Assets
Reconciliation of total segment assets to total assets
Assets	3,949,294	3,936,119
Operating segments | MPC Segment
Reconciliation of total segment assets to total assets
Assets	2,327,151	2,285,896
Operating segments | Seaport Segment
Reconciliation of total segment assets to total assets
Assets	972,512	924,245
Operating segments | Strategic Developments Segment
Reconciliation of total segment assets to total assets
Assets	1,212,919	1,132,231
Corporate
Reconciliation of total segment assets to total assets
Assets	$ 847,193	$ 861,841