Fair Value Measurements (Details 2) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Fair value of long-term debt estimated using quoted market prices or discounted future cash flows
Fair value of long-term debt	$ 259,280	$ 279,001
Fair value in excess of carrying value	$ 8,520	$ 7,908

Estimated fair value of the debt instrument at the balance-sheet date.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 107

-Paragraph 10

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