Convertible Debt and Notes Payable (Details)			3 Months Ended		12 Months Ended			40 Months Ended
		Oct. 10, 2014 USD ($)	Dec. 31, 2015 USD ($) letters_of_credit	Dec. 31, 2014 USD ($)	Dec. 31, 2015 USD ($) letters_of_credit	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Jan. 31, 2014 USD ($)	Mar. 10, 2014 USD ($) $ / shares
Debt and Capital Lease Obligations [Line Items]
Interest Expense, Lessee, Assets under Capital Lease			$ 100,000	$ 100,000	$ 100,000	$ 200,000
Components of short-term borrowings and other debt
Convertible debt	[1]		124,777,000	118,475,000	124,777,000	118,475,000
Revolver			5,000,000	0	5,000,000	0
Capital lease obligations			2,734,000	3,894,000	2,734,000	3,894,000
Debt, Long-term and Short-term, Combined Amount			195,761,000	185,619,000	195,761,000	185,619,000
Debt Instrument, Face Amount			63,250,000	63,250,000	63,250,000	63,250,000
Amortization of debt discount					6,302,000	4,685,000	$ 0
Cash convertible note hedge transaction					0	149,500,000	0
Capital Lease Obligations Incurred								$ 7,600,000
Capital Leases, Income Statement, Interest Expense					200,000	200,000	$ 100,000
Future minimum lease payments for capital lease obligations
2016			1,025,000		1,025,000
2017			938,000		938,000
2018			938,000		938,000
2019			78,000		78,000
2020			0		0
Thereafter			0		0
Subtotal			2,979,000		2,979,000
Less: Amount representing interest	[2]		(245,000)		(245,000)
Capital lease obligations			$ 2,734,000	3,894,000	$ 2,734,000	3,894,000
Number of Letters of Credit | letters_of_credit			8		8
Revolving Credit Facility
Components of short-term borrowings and other debt
Revolver			$ 5,000,000		$ 5,000,000
Letter of credit, borrowing capacity			$ 25,000,000		$ 25,000,000
Line of Credit Facility, Commitment Fee Percentage					3.00%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage					0.38%
Interest Expense, Debt					$ 200,000
Minimum
Components of short-term borrowings and other debt
Capital Lease Obligation, Initial Term					48 months
Capital leases, interest rate			0.60%		0.60%
Maximum
Components of short-term borrowings and other debt
Capital Lease Obligation, Initial Term					60 months
Capital leases, interest rate			6.03%		6.03%
Cash Convertible Note Economic Hedge And Warrant Transaction
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 January 2016 | Letter of Credit
Components of short-term borrowings and other debt
Letter of credit, borrowing capacity			$ 710,000		$ 710,000
Letter of Credit, NY Office, Expires February 2016 | Letter of Credit
Components of short-term borrowings and other debt
Letter of credit, borrowing capacity			1,000,000		1,000,000
Letter of Credit, Boston Office, Expires March 2016 | Letter of Credit
Components of short-term borrowings and other debt
Letter of credit, borrowing capacity			382,000		382,000
Letter of Credit, NY Office 1, Expires May 2016 | Letter of Credit
Components of short-term borrowings and other debt
Letter of credit, borrowing capacity			355,000		355,000
Letter of Credit, NY Office 2, Expires May 2016 | Letter of Credit
Components of short-term borrowings and other debt
Letter of credit, borrowing capacity			1,861,000		1,861,000
Letter of Credit, NY Office 3, Expires October 2016 | Letter of Credit
Components of short-term borrowings and other debt
Letter of credit, borrowing capacity			794,000		794,000
Letter of Credit, NY Office 4, Expires October 2016 | Letter of Credit
Components of short-term borrowings and other debt
Letter of credit, borrowing capacity			3,373,000		3,373,000
Letter of Credit, NY Office 5, Expires November 2016 | Letter of Credit
Components of short-term borrowings and other debt
Letter of credit, borrowing capacity			1,600,000		1,600,000
Convertible Debt
Components of short-term borrowings and other debt
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			1,100,000	1,100,000	4,500,000	3,600,000
Debt Instrument, Convertible, Conversion Price | $ / shares									$ 5.33
Convertible debt, unamortized discount			24,700,000	$ 31,000,000	24,700,000	31,000,000			$ 35,700,000
Amortization of debt discount					6,300,000	$ 4,700,000
Debt Instrument, Interest Rate, Effective Percentage									8.89%
Debt Issuance Cost					3,700,000
Repayments on long-term and short-term borrowings
2016			4,485,000		4,485,000
2017			4,485,000		4,485,000
2018			4,485,000		4,485,000
2019			151,743,000		151,743,000
2020			0		0
Thereafter			0		0
Subtotal			165,198,000		165,198,000
Less: Amount representing interest	[2]		(40,421,000)		(40,421,000)
Senior Notes
Components of short-term borrowings and other debt
Notes Payable			63,250,000		63,250,000
Debt Instrument, Face Amount		$ 63,300,000
Interest rate		8.25%
Interest on Convertible Debt, Net of Tax					5,200,000
Debt Issuance Cost		$ 2,900,000
Repayments on long-term and short-term borrowings
2016			5,218,000		5,218,000
2017			5,218,000		5,218,000
2018			5,218,000		5,218,000
2019			5,218,000		5,218,000
2020			5,218,000		5,218,000
Thereafter			68,468,000		68,468,000
Subtotal			94,558,000		94,558,000
Less: Amount representing interest	[2]		$ (31,308,000)		$ (31,308,000)
Common Stock Class A
Components of short-term borrowings and other debt
Class of Warrant, Exercise Price of Warrants or Rights | $ / shares									$ 7.18

[1] The carrying amount of the convertible debt includes an unamortized discount of $24.7 million and $31.0 million as of December 31, 2015 and 2014.

[2] Amount necessary to reduce net minimum payments to present value calculated at the Company's implicit rate at inception. This amount also includes the unamortized discount on the convertible debt.