Consolidated Statements of Shareholders' Equity (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Consolidated Statements of Shareholders' Equity and Comprehensive Income [Abstract]
Change in fair value of available-for-sale securities, tax effect	$ (3,629)	$ 9,951
Change in pension funding status, tax effect	$ 4,774		$ 10,376
Cash dividends declared (in dollars per share)		$ 0.25