Cash Collateral Pledged	9 Months Ended
Cash Collateral Pledged	Sep. 30, 2017
Cash and Cash Equivalents [Abstract]
Cash Collateral Pledged	Cash Collateral Pledged As of September 30, 2017 and December 31, 2016, the Company pledged cash collateral in the amount of $6.6 million and $7.8 million, respectively, which relates to letters of credit issued to the landlords of the Company's premises in New York City, Boston, Stamford and San Francisco. The Company also has pledged as collateral, $10.4 million, as of September 30, 2017, and $5.5 million, as of December 31, 2016, due between March 2018 and December 2019, for reinsurance agreements (See Note 17).

The entire disclosure for cash and cash equivalent footnotes, which may include the types of deposits and money market instruments, applicable carrying amounts, restricted amounts and compensating balance arrangements. Cash and equivalents include: (1) currency on hand (2) demand deposits with banks or financial institutions (3) other kinds of accounts that have the general characteristics of demand deposits (4) short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Generally, only investments maturing within three months from the date of acquisition qualify.