Goodwill and Intangible Assets (Details Textual) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Goodwill and Intangible Assets (Textual) [Abstract]
Amortization expense for acquired intangible assets	$ 1.7	$ 0.7	$ 3.0	$ 1.4

The aggregate expense charged against earnings to allocate the cost of acquired intangible assets. As a noncash expense, this element is added back to net income when calculating cash provided by (used in) operations using the indirect method.

No definition available.

Name:	us-gaap_AmortizationOfAcquiredIntangibleAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration