Convertible Debt and Short Term Borrowings (Details) (USD $)	3 Months Ended			6 Months Ended			40 Months Ended		6 Months Ended										3 Months Ended		6 Months Ended			6 Months Ended
	Jun. 30, 2014 letters_of_credit		Jun. 30, 2013	Jun. 30, 2014 letters_of_credit		Jun. 30, 2013	Jan. 31, 2014	Dec. 31, 2013	Jun. 30, 2014 Minimum	Jun. 30, 2014 Maximum	Jun. 30, 2014 Transaction [Domain]	Jun. 30, 2014 Treasury Stock	Jun. 30, 2014 Letter of Credit, NY Office, Expires June 2015 Letter of Credit	Jun. 30, 2014 Letter of Credit, NY Office, Expires February 2015 Letter of Credit	Jun. 30, 2014 Letter of Credit, NY Office, Expires December 2014 Letter of Credit	Jun. 30, 2014 Letter of Credit, NY Office, Expires September 2014 Letter of Credit	Jun. 30, 2014 Letter of Credit, Boston Office, Expires March 2015 Letter of Credit	Jun. 30, 2014 Letter of Credit, San Francisco Office, Expires May 2015 Letter of Credit	Jun. 30, 2014 Convertible Debt		Jun. 30, 2014 Convertible Debt		Mar. 10, 2014 Convertible Debt	Jun. 30, 2014 Insurance Note		Jan. 30, 2014 Insurance Note
Debt and Capital Lease Obligations [Line Items]
Number of Letters of Credit	6			6
Components of short-term borrowings and other debt
Convertible debt	$ 115,549,000			$ 115,549,000				$ 0											$ 115,549,000		$ 115,549,000
Notes payable	893,000			893,000				41,000																893,000		2,000,000
Capital lease obligations	4,605,000			4,605,000				2,523,000
Debt, Long-term and Short-term, Combined Amount	121,047,000			121,047,000				2,564,000
Debt Instrument, Unamortized Premium																			34,000,000		34,000,000
Interest rate																							3.00%			1.55%
Debt Instrument, Face Amount																							149,500,000
Interest on Convertible Debt, Net of Tax																			1,100,000		1,400,000
Principal amount of notes being converted																							1,000
Debt Instrument, Convertible, Conversion Price																							$ 5.33
Discount on debt																							35,700,000
Amortization of Debt Discount				1,759,000		0													1,400,000		1,800,000
Debt Instrument, Interest Rate, Effective Percentage																							8.89%
Debt Instrument, Fair Value Disclosure	157,400,000			157,400,000
Debt Issuance Cost																					3,700,000
Cash convertible note hedge transaction				149,500,000		0					20,500,000	300,000
Class of Warrant, Exercise Price of Warrants or Rights																							7.18
Monthly payment																								200,000
Capital Lease Obligations Incurred							7,600,000
Capital Lease Obligation, Initial Term									48 months	60 months
Capital leases, interest rate									0.60%	6.03%
Capital lease interest expense	100,000		100,000	100,000		100,000
Letter of credit, borrowing capacity													1,861,000	1,000,000	4,497,000	892,000	382,000	82,000
Future minimum lease payments for capital lease obligations
Capital leases, Future Minimum Payments Due, Remainder of Fiscal Year	824,000			824,000
Capital Leases, Future Minimum Payments Due in Two Years	1,343,000			1,343,000
Capital Leases, Future Minimum Payments Due in Three Years	1,025,000			1,025,000
Capital Leases, Future Minimum Payments Due in Four Years	938,000			938,000
Capital Leases, Future Minimum Payments Due in Five Years	938,000			938,000
Capital Leases, Future Minimum Payment Due Thereafter	79,000			79,000
Subtotal	5,147,000			5,147,000
Less: Amount representing interest	(542,000)	[1]		(542,000)	[1]
Capital lease obligations	4,605,000			4,605,000				2,523,000
Repayments on long-term and short-term borrowings
Notes Payable, Repayments Due Remainder of Fiscal Year																			2,284,000		2,284,000			905,000
Notes Payable, Repayments in Year Two																			4,411,000		4,411,000			0
Notes Payable, Repayments in Year Three																			4,411,000		4,411,000			0
Notes Payable, Repayments in Year Four																			4,411,000		4,411,000			0
Notes Payable, Repayments in Year Five																			4,411,000		4,411,000			0
Notes Payable, Repayments Due after Year Five																			151,688,000		151,688,000			0
Subtotal																			171,616,000		171,616,000			905,000
Less: Amount representing interest																			(56,067,000)	[1]	(56,067,000)	[1]		(12,000)	[1]
Notes payable	$ 893,000			$ 893,000				$ 41,000																$ 893,000		$ 2,000,000

[1] 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.