Agreement with SK hynix and Micron (Details 2) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	4 Months Ended	3 Months Ended	4 Months Ended	3 Months Ended	4 Months Ended	3 Months Ended	10 Months Ended	3 Months Ended	10 Months Ended	3 Months Ended	10 Months Ended
	Mar. 31, 2014 Micron [Member]	Mar. 31, 2014 Micron [Member]	Mar. 31, 2014 Micron [Member] Royalty revenue	Mar. 31, 2014 Micron [Member] Royalty revenue	Mar. 31, 2014 Micron [Member] Gain from settlement	Mar. 31, 2014 Micron [Member] Gain from settlement	Mar. 31, 2014 SK hynix [Member]	Mar. 31, 2014 SK hynix [Member]	Mar. 31, 2014 SK hynix [Member] Royalty revenue	Mar. 31, 2014 SK hynix [Member] Royalty revenue	Mar. 31, 2014 SK hynix [Member] Gain from settlement	Mar. 31, 2014 SK hynix [Member] Gain from settlement
Accounts, Notes, Loans and Financing Receivable [Line Items]
Cash Received to date in 2014	$ 10.0	$ 15.5	$ 9.7	$ 15.0	$ 0.3	$ 0.5	$ 12.0	$ 36.0	$ 11.8	$ 35.4	$ 0.2	$ 0.6
Estimated to Be Received in Remainder of 2014	30.0	30.0	29.0	29.0	1.0	1.0	36.0	36.0	35.5	35.5	0.5	0.5
Estimated to Be Received in 2015	40.0	40.0	38.7	38.7	1.3	1.3	48.0	48.0	47.3	47.3	0.7	0.7
Estimated to Be Received in 2016	40.0	40.0	39.5	39.5	0.5	0.5	48.0	48.0	47.9	47.9	0.1	0.1
Estimated to Be Received in 2017	40.0	40.0	40.0	40.0	0	0	48.0	48.0	48.0	48.0	0	0
Estimated to Be Received in 2018	40.0	40.0	40.0	40.0	0	0	24.0	24.0	24.0	24.0	0	0
Estimated to Be Received in 2019 and thereafter	74.5	74.5	74.5	74.5	0	0
Total Estimated Cash receipts	$ 280.0	$ 280.0	$ 276.7	$ 276.7	$ 3.3	$ 3.3	$ 240.0	$ 240.0	$ 238.1	$ 238.1	$ 1.9	$ 1.9