Marketable Securities and Fair Value Measurements (Details 1) - USD ($) $ in Thousands | Mar. 31, 2016 | Dec. 31, 2015 |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale Securities | $ 81,929 | $ 81,016 |
Equity Securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale Securities | 2,018 | 1,891 |
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 | 43,458 | 40,685 |
Corporate Bonds And Preferred Equities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale Securities | 33,366 | 34,985 |
Collateralized Mortgage Backed Securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale Securities | 3,087 | 3,455 |
Fair Value, Inputs, Level 1 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale Securities | 2,018 | 1,891 |
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 | 2,018 | 1,891 |
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] | Collateralized Mortgage Backed 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] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale Securities | 79,911 | 79,125 |
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 | 43,458 | 40,685 |
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 | 33,366 | 34,985 |
Fair Value, Inputs, Level 2 [Member] | Collateralized Mortgage Backed Securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale Securities | 3,087 | 3,455 |
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] | Collateralized Mortgage Backed Securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale Securities | $ 0 | $ 0 |