Condensed Consolidated Statements of Cash Flows (Parenthetical)	12 Months Ended
Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Statement of Cash Flows [Abstract]
6.1 million shares of NPS common stock issued	6.1	0	0

This element represents movements in the number of shares included in the statement of changes in stockholders' equity which are not separately disclosed or provided for elsewhere in the taxonomy.

No definition available.

Name:	us-gaap_StockholdersEquityOtherShares
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration