Financing Arrangements - Expenses in Relation to Convertible Notes (Details) - USD ($) $ in Thousands	3 Months Ended												6 Months Ended			9 Months Ended			12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2013	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Amortization of Financing Costs	$ 1,175	$ 1,086	$ 1,026	$ 996	$ 1,116	$ 2,272	$ 2,346	$ 4,251	$ 220	$ 211	$ 207	$ 204	$ 2,022	$ 6,597	$ 411	$ 3,108	$ 8,869	$ 622	$ 4,283	$ 9,985	$ 842
Convertible Debt [Member]
Debt Instrument [Line Items]
Interest expense at 3.50% coupon rate																			2,205	4,105	4,200
Debt discount amortization																			2,421	4,317	4,113
Amortization of Financing Costs																			438	780	744
Loss on conversion																			1,235	990
Interest expense																			$ 6,299	$ 10,192	$ 9,057