Fair Value Measurements (Details) (Textuals) (USD $) In Millions, unless otherwise specified	1 Months Ended
Mar. 31, 2010	Jun. 30, 2011	Dec. 31, 2010
Fair Value Measurements (Textuals) [Abstract]
Notional amount of interest rate swap	$ 150	$ 150
Semi-annual interest payments at a fixed rate	6.875%	6.875%
Variable interest rate, Adjustment	90 days	90 days
Termination date of Swap agreement	Jun. 01, 2014
Fair value of long-term debt		$ 1,212.4	$ 902.5

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6947722&loc=d3e13433-108611

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=6947722&loc=d3e13476-108611

Name:	us-gaap_DebtInstrumentFairValue
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant