Marketable Securities and Fair Value Measurements (Details 1) - USD ($) $ in Thousands | Mar. 31, 2017 | Dec. 31, 2016 |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale Securities | $ 51,271 | $ 52,495 |
Equity Securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale Securities | 1,676 | 1,730 |
Marco OP and Marco OP II Units [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale Securities | 35,996 | 37,176 |
Corporate Bonds And Preferred Equities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale Securities | 11,452 | 10,985 |
MBS [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale Securities | 2,147 | 2,604 |
Fair Value, Inputs, Level 1 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale Securities | 1,676 | 1,730 |
Fair Value, Inputs, Level 1 [Member] | Equity Securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale Securities | 1,676 | 1,730 |
Fair Value, Inputs, Level 1 [Member] | Marco OP and Marco OP II Units [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale Securities | 0 | 0 |
Fair Value, Inputs, Level 1 [Member] | Corporate Bonds And Preferred Equities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale Securities | 0 | 0 |
Fair Value, Inputs, Level 1 [Member] | MBS [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale Securities | 0 | 0 |
Fair Value, Inputs, Level 2 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale Securities | 49,595 | 50,765 |
Fair Value, Inputs, Level 2 [Member] | Equity Securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale Securities | 0 | 0 |
Fair Value, Inputs, Level 2 [Member] | Marco OP and Marco OP II Units [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale Securities | 35,996 | 37,176 |
Fair Value, Inputs, Level 2 [Member] | Corporate Bonds And Preferred Equities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale Securities | 11,452 | 10,985 |
Fair Value, Inputs, Level 2 [Member] | MBS [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale Securities | 2,147 | 2,604 |
Fair Value, Inputs, Level 3 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale Securities | 0 | 0 |
Fair Value, Inputs, Level 3 [Member] | Equity Securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale Securities | 0 | 0 |
Fair Value, Inputs, Level 3 [Member] | Marco OP and Marco OP II Units [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale Securities | 0 | 0 |
Fair Value, Inputs, Level 3 [Member] | Corporate Bonds And Preferred Equities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale Securities | 0 | 0 |
Fair Value, Inputs, Level 3 [Member] | MBS [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale Securities | $ 0 | $ 0 |