Fair Value (Assets Measured on a Non-recurring Basis) (Details) - Century Park - Fair Value, Measurements, Nonrecurring - Strategic Developments Segment $ in Thousands	Jun. 30, 2021 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value on non-recurring basis	$ 32,000
Fair Value Measurements Using Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value on non-recurring basis	0
Fair Value Measurements Using Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value on non-recurring basis	0
Fair Value Measurements Using Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value on non-recurring basis	$ 32,000