Summary of Significant Accounting Policies (Details) (USD $)	1 Months Ended		3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Summary of Significant Accounting Policies (Textual) [Abstract]
Authorized amount from board of directors for share repurchase		$ 200,000,000
Share repurchase program effective date		Oct. 01, 2012
Share repurchase program expiry date		Dec. 31, 2014
Shares repurchased under the program			539,941	141,992	1,834,189	1,834,221
Cost of shares repurchased			23,900,000	4,000,000	73,800,000	45,200,000
Shares repurchased settled in subsequent month	$ 2,700,000
Customer receivables concentration | Customer receivables concentration | Energy Equipment Group
Summary of Significant Accounting Policies (Textual) [Abstract]
Number of customers for net receivables concentration					1
Net receivables percentage					14.00%