Share-Based Compensation - Summary Of ESPP Annual Offerings (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Amount expensed under ESPP	$ 3,542	$ 3,080	$ 2,607
Employee Stock Purchase Plan (ESPP)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common shares purchased (in shares)	59	55	65
Per common share purchase Price (in dollars per share)	$ 26.29	$ 24.11	$ 19.75
Amount expensed under ESPP	$ 509	$ 375	$ 562
Net proceeds from issuance	$ 1,558	$ 1,326	$ 1,288
Common shares date of issue	Jan. 06, 2016	Jan. 07, 2015	Jan. 03, 2014