Summary of Significant Accounting Policies (Segment Reporting) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012 segments	Dec. 31, 2011	Dec. 31, 2010
Revenue from External Customer [Line Items]
Number of operating segments									1
Total Net Revenues	$ 351,777	$ 98,536	$ 99,020	$ 91,291	$ 263,754	$ 76,523	$ 75,764	$ 57,229	$ 640,624	$ 473,270	$ 307,707
Consumer [Member]
Revenue from External Customer [Line Items]
Total Net Revenues									613,445	459,725	302,599
Enterprise [Member]
Revenue from External Customer [Line Items]
Total Net Revenues									$ 27,179	$ 13,545	$ 5,108