Cash collateral pledged	12 Months Ended
Cash collateral pledged	Dec. 31, 2013
Cash and Cash Equivalents [Abstract]
Cash collateral pledged	Cash collateral pledged As of December 31, 2013 and 2012, the Company pledged cash collateral in the amount of $10.9 million and $9.2 million, respectively, which relates to letters of credit issued to the landlords of the Company's premises in New York City and San Francisco (see Note 20).

Entity's cash and cash equivalents accounting policy with respect to restricted balances. Restrictions may include legally restricted deposits held as compensating balances against short-term borrowing arrangements, contracts entered into with others, or company statements of intention with regard to particular deposits; however, time deposits and short-term certificates of deposit are not generally included in legally restricted deposits.

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