Subsequent Events	6 Months Ended
Subsequent Events	Jun. 30, 2021
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events On August 5, 2021, Newmark declared a qualified quarterly dividend of $0.01 per share payable on September 7, 2021 to Class A and Class B common stockholders of record as of August 20, 2021. The ex-dividend date will be August 19, 2021. Borrowing facility On August 2, 2021, a subsidiary of Newmark, Newmark OpCo, entered into a Master Repurchase Agreement (the “Repurchase Agreement”) with CF Secured, LLC (“CF Secured”), an affiliate of Newmark’s majority stockholder, Cantor, pursuant to which Newmark may seek, from time-to-time, to execute short-term secured financing transactions. Repurchase agreements effect equity financing. The Company, under the Repurchase Agreement, may seek to sell securities, in this case common shares of Nasdaq, owned by the Company, to CF Secured, under the Repurchase Agreement, and agrees to repurchase those securities on a date certain at a repurchase price generally equal to the original purchase price plus interest. Pursuant to the Repurchase Agreement, the Company and CF Secured agreed to enter into a repurchase transaction, wherein CF Secured will deliver the cash of such repurchase transaction to the Company on an overnight basis at an initial rate of 0.95% per annum (approximately 1.00% less expensive than Newmark’s revolving credit facility), and the Company will deliver to CF Secured the number of shares of Nasdaq as collateral so that the market value of such shares equals 130% of such cash proceeds. The Nasdaq shares will be marked to market daily, and the minimum maintenance margin requirement, should the share price decline, will be 120% of such cash proceeds. The Company will be required to transfer additional collateral (securities and/or cash) in the event of a margin percentage decline below 120%. The initial repurchase or financing transaction was executed on August 2, 2021 and consisted of Newmark receiving $260 million in cash and delivering 1,818,000 Nasdaq shares as collateral. The repurchase transaction may be rolled over daily (or for a term greater than one day at a time), subject to terms mutually acceptable to the Company and CF Secured, including the rate and minimum margin requirement, both of which can fluctuate based upon general funding rates and other factors in the repurchase funding market. The Repurchase Agreement is subject to ongoing compliance with various covenants and contains customary events of default. If an event of default occurs, the repurchase date for each transaction under the Repurchase Agreement may be accelerated to the date of default. For events of default relating to insolvency and receivership, the repurchase date for each transaction under the Repurchase Agreement is automatically accelerated to the date of default. Newmark still receives dividends on the common shares of Nasdaq it owns, including those shares used as collateral. The Company intends to utilize the cash proceeds from the repurchase transaction to fund the cash portion of the 2021 Equity Event and to pay taxes. The Company expects to repay the cash proceeds under the repurchase transaction with the proceeds of periodic sales of Nasdaq shares and from its operating cash. The Repurchase Agreement and related initial repurchase transaction are on market terms and rates and were approved by Newmark’s Audit Committee. On August 5, 2021, the Board and Audit Committee authorized the $400.0 million Newmark share repurchase and unit redemption authorization, which may include purchases from Cantor, its partners or employees or other affiliated persons or entities.