Severance Benefits (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Dec. 31, 2013
Notes To Consolidated Financial Statements [Abstract]
Description Of Postemployment Benefits	Severance Benefits In the first quarter of 2014, NU recorded severance benefit expenses of $4.3 million associated with the partial outsourcing of information technology functions and ongoing post-merger integration. As of March 31, 2014 and December 31, 2013, the severance accrual totaled $17.7 million and $14.7 million, respectively, and was included in Other Current Liabilities on the balance sheets.
Postemployment Benefits Period Expense	$ 4.3
Postemployment Benefits Liability Current And Noncurrent	$ 17.7	$ 14.7