Share-based Compensation - Allocation of Share-based Compensation Expense and Additional Disclosures (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated share-based compensation expense	$ 8,122	$ 15,328	$ 36,609
Share based compensation expense per share, basic (in usd per share)	$ 0.11	$ 0.20	$ 0.48
Share based compensation expense per share, diluted (in usd per share)	$ 0.11	$ 0.20	$ 0.48
Cost of Service [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated share-based compensation expense	254	1,734	3,673
Selling and Marketing Expense [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated share-based compensation expense	22	1,985	5,781
General and Administrative Expense [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated share-based compensation expense	$ 7,846	$ 11,609	$ 27,155