Summary of Significant Accounting Policies Level 4 Revisions to Prior Period Financial Statements (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended				3 Months Ended	6 Months Ended	9 Months Ended	12 Months Ended		3 Months Ended	6 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Mar. 31, 2013 As Reported [Member]	Jun. 30, 2013 As Reported [Member]	Sep. 30, 2013 As Reported [Member]	Dec. 31, 2012 As Reported [Member]	Dec. 31, 2011 As Reported [Member]	Mar. 31, 2013 As Revised [Member]	Jun. 30, 2013 As Revised [Member]	Sep. 30, 2013 As Revised [Member]	Dec. 31, 2012 As Revised [Member]	Dec. 31, 2011 As Revised [Member]
Cash and cash equivalents	$ 118,249	$ 45,893	$ 176,369	$ 259,135	$ 233,547	$ 232,667	$ 157,019	$ 54,507		$ 221,232	$ 223,881	$ 144,216	$ 45,893
Total current assets	687,705	518,843			857,862	845,385	769,568	527,457		845,547	836,599	756,765	518,843
Total assets	1,104,186	827,784	896,700		1,209,797	1,194,615	1,217,959	836,398		1,197,482	1,185,829	1,205,156	827,784
Accounts payable					218,480	197,163	193,772	142,142		206,165	188,377	180,969	133,528
Total current liabilities	239,017	227,573			301,111	272,822	301,815	236,187		288,796	264,036	289,012	227,573
Total liabilities and stockholders' equity	1,104,186	827,784			1,209,797	1,194,615	1,217,959	836,398		1,197,482	1,185,829	1,205,156	827,784
Net cash provided by (used for) operations	$ 33,427	$ 77,608	$ (43,601)		$ (53,742)	$ (45,823)	$ 22,077	$ 80,136	$ (42,981)	$ (57,443)	$ (45,995)	$ 17,888	$ 77,608	$ (43,601)