Fair Value Measurements (Details 2) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Assets:
Marketable securities in deferred compensation plan	$ 3,868	$ 4,616
Fair value measurement on a recurring basis [Member]
Assets:
Interest rate derivatives	5,617	3,073
Total assets	9,485	7,689
Liabilities:
Deferred compensation plan liability	3,868	4,616
Interest rate derivatives	5,459
Total liabilities	9,327
Fair value measurement on a recurring basis [Member] | Mutual funds [Member]
Assets:
Marketable securities in deferred compensation plan	3,819	4,547
Fair value measurement on a recurring basis [Member] | Other [Member]
Assets:
Marketable securities in deferred compensation plan	49	69
Fair value measurement on a recurring basis [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Assets:
Total assets	3,868	4,616
Fair value measurement on a recurring basis [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Mutual funds [Member]
Assets:
Marketable securities in deferred compensation plan	3,819	4,547
Fair value measurement on a recurring basis [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Other [Member]
Assets:
Marketable securities in deferred compensation plan	49	69
Fair value measurement on a recurring basis [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets:
Interest rate derivatives	5,617	3,073
Total assets	5,617	3,073
Liabilities:
Deferred compensation plan liability	3,868	4,616
Interest rate derivatives	5,459
Total liabilities	9,327
Corporate Office Properties, L.P. [Member] | Fair value measurement on a recurring basis [Member]
Assets:
Interest rate derivatives	5,617	3,073
Liabilities:
Interest rate derivatives	5,459
Corporate Office Properties, L.P. [Member] | Fair value measurement on a recurring basis [Member] | Significant Other Observable Inputs (Level 2) [Member]
Assets:
Interest rate derivatives	5,617	$ 3,073
Liabilities:
Interest rate derivatives	$ 5,459