Leases (Details 2) - Capital Leases, Leased Assets and Future Lease Payments (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Future capital lease payments under non-cancelable leases
2014	$ 39,221
2015	17,448
2016	2,242
2017	622
2018	635
Thereafter	3,819
Total minimum capital lease payments	63,987
Less amount representing interest	(1,054)
Present value of net minimum lease payments	62,933
Less current portion of obligations under capital leases	(37,885)	(61,302)
Non-current obligations under capital leases	25,048	60,335
Computers, software and equipment
Amounts in property and equipment under capital leases
Capital leased assets, gross	391,833	389,720
Less: Accumulated depreciation and amortization	(335,599)	(272,708)
Capital leased assets, net	56,234	117,012
Work in process
Amounts in property and equipment under capital leases
Capital leased assets, gross	$ 6,800