Employee Benefit Plans (Details 6) (Employee Pension Plans, USD $) In Thousands, unless otherwise specified				12 Months Ended				12 Months Ended				12 Months Ended				12 Months Ended				12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Significant unobservable inputs (Level 3)	Dec. 31, 2012 Significant unobservable inputs (Level 3)	Dec. 31, 2013 Hedge Fund Investments, Long-Short Equity Fund	Dec. 31, 2012 Hedge Fund Investments, Long-Short Equity Fund	Dec. 31, 2013 Hedge Fund Investments, Long-Short Equity Fund Significant unobservable inputs (Level 3)	Dec. 31, 2012 Hedge Fund Investments, Long-Short Equity Fund Significant unobservable inputs (Level 3)	Dec. 31, 2013 Hedge Fund Investments, Event Driven Fund	Dec. 31, 2012 Hedge Fund Investments, Event Driven Fund	Dec. 31, 2013 Hedge Fund Investments, Event Driven Fund Significant unobservable inputs (Level 3)	Dec. 31, 2012 Hedge Fund Investments, Event Driven Fund Significant unobservable inputs (Level 3)	Dec. 31, 2013 Hedge Funds, Distressed Credit	Dec. 31, 2012 Hedge Funds, Distressed Credit	Dec. 31, 2013 Hedge Funds, Distressed Credit Significant unobservable inputs (Level 3)	Dec. 31, 2012 Hedge Funds, Distressed Credit Significant unobservable inputs (Level 3)	Dec. 31, 2013 Hedge Fund Investments, Multi-Strategy Fund	Dec. 31, 2012 Hedge Fund Investments, Multi-Strategy Fund	Dec. 31, 2013 Hedge Fund Investments, Multi-Strategy Fund Significant unobservable inputs (Level 3)	Dec. 31, 2012 Hedge Fund Investments, Multi-Strategy Fund Significant unobservable inputs (Level 3)
Change in Fair Value of Plan Assets
Balance at beginning of year	$ 72,617	$ 66,137	$ 62,105	$ 21,653	$ 29,729	$ 26,221	$ 19,818	$ 9,992	$ 12,821	$ 14,680	$ 13,694	$ 7,152	$ 7,126	$ 1,429	$ 5,388	$ 2,559	$ 6,252	$ 1,888	$ 2,839	$ 1,950	$ 3,530
Realized gains (losses)				(12)	7											(7)	5			(5)	2
Unrealized gains (losses)				4,604	2,684			2,971	1,624			1,252	522			158	365			223	173
Purchases				1,817	9,392			1,343	5,555			459	3,798			6	20			9	19
Sales				(895)	(1,667)											(517)	(894)			(378)	(773)
Transfer to Level 2				(3,443)	(18,492)			(3,443)	(10,008)				(4,294)				(3,189)				(1,001)
Balance at end of year	$ 72,617	$ 66,137	$ 62,105	$ 23,724	$ 21,653	$ 26,221	$ 19,818	$ 10,863	$ 9,992	$ 14,680	$ 13,694	$ 8,863	$ 7,152	$ 1,429	$ 5,388	$ 2,199	$ 2,559	$ 1,888	$ 2,839	$ 1,799	$ 1,950
Transfer comprised of hedge funds redeemable period of time				90 days	90 days