Related Party Transactions (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Related party transactions
Lease payments to related party	$ 1,505	$ 1,556	$ 1,342
SIGI
Related party transactions
Lease payments to related party	862	907	929
Roger Newnham
Related party transactions
Lease payments to related party	289	295	292
Lemmie Rockford
Related party transactions
Lease payments to related party	90	90	90
Quality RE Partners
Related party transactions
Lease payments to related party	$ 264	$ 264
Number of former shareholders owning leased property	3
Number of current employees owning leased property	2