Dividends (Details) (USD $)	0 Months Ended	12 Months Ended
	Dec. 27, 2012	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Dividends, Common Stock [Abstract]
Payment of cash dividends		$ 11,299,000	$ 8,219,000	$ 12,072,000
Dividends paid per common share		$ 0.2	$ 0.1425	$ 0.205
Accelerated cash dividend per share	$ 0.0425
Payment of accelerated cash dividends	$ 2,500,000