Summary of Significant Accounting Policies (Details Textual) - USD ($)	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Accounting Policies [Abstract]
Authorized amount from board of directors for share repurchase	$ 250,000,000
Shares repurchased under the program (in shares)	2,070,600	721,040
Cost of shares repurchased	$ 34,700,000	$ 25,000,000