Convertible Debt and Notes Payable (Details)			3 Months Ended		40 Months Ended
		Oct. 10, 2014 USD ($)	Mar. 31, 2016 USD ($) letters_of_credit	Mar. 31, 2015 USD ($)	Jan. 31, 2014 USD ($)	Jan. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Mar. 10, 2014 USD ($) $ / shares
Debt and Capital Lease Obligations [Line Items]
Interest Expense, Lessee, Assets under Capital Lease			$ 100,000	$ 100,000
Components of short-term borrowings and other debt
Convertible debt	[1]		124,251,000				$ 122,401,000
Revolver			25,000,000				5,000,000
Capital lease obligations			2,450,000				2,734,000
Debt, Long-term and Short-term, Combined Amount			214,332,000				190,966,000
Debt Instrument, Face Amount			60,936,000				60,831,000
Amortization of debt discount			1,665,000	1,524,000
Other Notes Payable			1,695,000				0
Capital Lease Obligations Incurred					$ 7,600,000
Capital Leases, Income Statement, Interest Expense			100,000	100,000
Future minimum lease payments for capital lease obligations
2016			704,000
2017			938,000
2018			938,000
2019			78,000
2020			0
Thereafter			0
Subtotal			2,658,000
Less: Amount representing interest	[2]		(208,000)
Capital lease obligations			$ 2,450,000				2,734,000
Number of Letters of Credit | letters_of_credit			9
Revolving Credit Facility
Components of short-term borrowings and other debt
Revolver			$ 25,000,000
Letter of credit, borrowing capacity			$ 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			$ 100,000
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%
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 2017 | Letter of Credit
Components of short-term borrowings and other debt
Letter of credit, borrowing capacity			$ 710,000
Letter of Credit, NY Office, Expires January 2017 [Member] | Letter of Credit
Components of short-term borrowings and other debt
Letter of credit, borrowing capacity			65,000
Letter of Credit, NY Office, Expires February 2017 | Letter of Credit
Components of short-term borrowings and other debt
Letter of credit, borrowing capacity			1,000,000
Letter of Credit, Boston Office, Expires March 2017 | Letter of Credit
Components of short-term borrowings and other debt
Letter of credit, borrowing capacity			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
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
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
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
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
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
Debt Instrument, Convertible, Conversion Price | $ / shares								$ 5.33
Convertible debt, unamortized discount			23,100,000				$ 24,700,000	$ 35,700,000
Amortization of debt discount			1,700,000	1,500,000
Debt Instrument, Interest Rate, Effective Percentage								8.89%
Debt Issuance Cost			3,700,000
Repayments on long-term and short-term borrowings
2016			2,243,000
2017			4,485,000
2018			4,485,000
2019			151,743,000
2020			0
Thereafter			0
Subtotal			162,956,000
Less: Amount representing interest	[2]		(38,705,000)
Senior Notes
Components of short-term borrowings and other debt
Notes Payable			60,936,000
Debt Instrument, Face Amount		$ 63,300,000
Interest rate		8.25%
Interest on Convertible Debt, Net of Tax			1,300,000	$ 1,300,000
Debt Issuance Cost		$ 2,900,000
Repayments on long-term and short-term borrowings
2016			3,914,000
2017			5,218,000
2018			5,218,000
2019			5,218,000
2020			5,218,000
Thereafter			68,468,000
Subtotal			93,254,000
Less: Amount representing interest	[2]		(32,318,000)
Insurance Note [Member]
Components of short-term borrowings and other debt
Long-term Debt, Maturities, Repayments of Principal, Remainder of Fiscal Year			1,718,000
Interest rate						1.38%
Debt Instrument, Periodic Payment, Principal			200,000
Short-term Debt, Maximum Amount Outstanding During Period			2,000,000
Other Notes Payable			1,695,000			$ 1,700,000
Repayments on long-term and short-term borrowings
2017			0
2018			0
2019			0
2020			0
Thereafter			0
Subtotal			1,718,000
Less: Amount representing interest	[2]		$ (23,000)
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 $23.1 million and $24.7 million as of March 31, 2016 and December 31, 2015.

[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.