Convertible Debt and Notes Payable (Details) (USD $)	12 Months Ended				40 Months Ended	0 Months Ended
	Dec. 31, 2014 letters_of_credit		Dec. 31, 2013	Dec. 31, 2012	Jan. 31, 2014	Oct. 10, 2014	Mar. 10, 2014	Jan. 30, 2014
Components of short-term borrowings and other debt
Convertible debt	$ 118,475,000	[1]	$ 0
Note Payable	63,250,000		0
Other Note payable	0		41,000
Capital lease obligations	3,894,000		2,523,000
Debt, Long-term and Short-term, Combined Amount	185,619,000		2,564,000
Amortization of Debt Discount	4,685,000		0	0
Cash convertible note hedge transaction	149,500,000		0	0
Capital Lease Obligations Incurred					7,600,000
Capital lease interest expense	200,000		100,000	200,000
Repayments on long-term and short-term borrowings
Convertible debt	118,475,000	[1]	0
Future minimum lease payments for capital lease obligations
2015	1,343,000
2016	1,025,000
2017	938,000
2018	938,000
2019	79,000
Thereafter	0
Subtotal	4,323,000
Less: Amount representing interest	(429,000)	[2]
Capital lease obligations	3,894,000		2,523,000
Number of Letters of Credit	7
Minimum
Components of short-term borrowings and other debt
Capital Lease Obligation, Initial Term	48 months
Capital leases, interest rate	0.60%
Maximum
Components of short-term borrowings and other debt
Capital Lease Obligation, Initial Term	60 months
Capital leases, interest rate	6.03%
Transaction [Domain]
Components of short-term borrowings and other debt
Cash convertible note hedge transaction	20,500,000
Treasury Stock
Components of short-term borrowings and other debt
Cash convertible note hedge transaction	300,000
Letter of Credit, San Francisco Office, Expires May 2015 | Letter of Credit
Future minimum lease payments for capital lease obligations
Letter of credit, borrowing capacity	82,000
Letter of Credit, Boston Office, Expires March 2015 | Letter of Credit
Future minimum lease payments for capital lease obligations
Letter of credit, borrowing capacity	382,000
Letter of Credit, NY Office, Expires August 2015 | Letter of Credit
Future minimum lease payments for capital lease obligations
Letter of credit, borrowing capacity	893,000
Letter of Credit, NY Office, Expires December 2015 | Letter of Credit
Future minimum lease payments for capital lease obligations
Letter of credit, borrowing capacity	3,935,000
Letter of Credit, NY Office, Expires February 2015 | Letter of Credit
Future minimum lease payments for capital lease obligations
Letter of credit, borrowing capacity	1,000,000
Letter of Credit, NY Office, Expires June 2015 | Letter of Credit
Future minimum lease payments for capital lease obligations
Letter of credit, borrowing capacity	1,861,000
Letter of Credit, NY Office, Expires September 2015 | Letter of Credit
Future minimum lease payments for capital lease obligations
Letter of credit, borrowing capacity	127,000
Convertible Debt
Components of short-term borrowings and other debt
Convertible debt	118,475,000
Debt Instrument, Face Amount							149,500,000
Interest rate							3.00%
Principal amount of notes being converted							1,000
Interest on Convertible Debt, Net of Tax	3,600,000
Debt Instrument, Convertible, Conversion Price							$ 5.33
Discount on debt							35,700,000
Amortization of Debt Discount	4,700,000
Debt Instrument, Interest Rate, Effective Percentage							8.89%
Debt Issuance Cost	3,700,000
Class of Warrant, Exercise Price of Warrants or Rights							$ 7.18
Repayments on long-term and short-term borrowings
2015	4,485,000
2016	4,485,000
2017	4,485,000
2018	4,485,000
2019	151,743,000
Thereafter	0
Subtotal	169,683,000
Less: Amount representing interest	(51,208,000)	[2]
Convertible debt	118,475,000
Senior Notes
Components of short-term borrowings and other debt
Convertible debt	63,250,000
Debt Instrument, Face Amount						63,300,000
Interest rate						8.25%
Interest on Convertible Debt, Net of Tax	1,200,000
Debt Issuance Cost						2,900,000
Repayments on long-term and short-term borrowings
2015	5,291,000
2016	5,218,000
2017	5,218,000
2018	5,218,000
2019	5,218,000
Thereafter	73,686,000
Subtotal	99,849,000
Less: Amount representing interest	(36,599,000)
Convertible debt	63,250,000
Insurance Note
Components of short-term borrowings and other debt
Other Note payable								2,000,000
Interest rate								1.55%
Monthly payment	$ 200,000

[1] The carrying amount of the convertible debt includes unamortized discount of $31.0 million.

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