Employee Benefit Plans, Changes in Fair Value of Level 3 Plan Assets (Details) (USD $) In Thousands, unless otherwise specified																								12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2011 Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2012 Hedge Fund Investments, Long-Short Equity Fund [Member]	Dec. 31, 2011 Hedge Fund Investments, Long-Short Equity Fund [Member]	Dec. 31, 2012 Hedge Fund Investments, Long-Short Equity Fund [Member] Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2011 Hedge Fund Investments, Long-Short Equity Fund [Member] Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2012 Hedge Fund Investments, Event Driven Fund [Member]	Dec. 31, 2011 Hedge Fund Investments, Event Driven Fund [Member]	Dec. 31, 2012 Hedge Fund Investments, Event Driven Fund [Member] Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2011 Hedge Fund Investments, Event Driven Fund [Member] Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2012 Hedge Funds, Distressed Credit [Member]	Dec. 31, 2011 Hedge Funds, Distressed Credit [Member]	Dec. 31, 2012 Hedge Funds, Distressed Credit [Member] Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2011 Hedge Funds, Distressed Credit [Member] Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2012 Hedge Fund Investments, Multi-Strategy Fund [Member]	Dec. 31, 2011 Hedge Fund Investments, Multi-Strategy Fund [Member]	Dec. 31, 2012 Hedge Fund Investments, Multi-Strategy Fund [Member] Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2011 Hedge Fund Investments, Multi-Strategy Fund [Member] Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2012 Defined Benefit Pension Plan and Benefit Equalization Plan [Member]	Dec. 31, 2011 Defined Benefit Pension Plan and Benefit Equalization Plan [Member]	Dec. 31, 2010 Defined Benefit Pension Plan and Benefit Equalization Plan [Member]	Dec. 31, 2012 Defined Benefit Pension Plan and Benefit Equalization Plan [Member] Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2011 Defined Benefit Pension Plan and Benefit Equalization Plan [Member] Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2012 Defined Benefit Pension Plan and Benefit Equalization Plan [Member] Hedge Fund Investments, Long-Short Equity Fund [Member] Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2011 Defined Benefit Pension Plan and Benefit Equalization Plan [Member] Hedge Fund Investments, Long-Short Equity Fund [Member] Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2012 Defined Benefit Pension Plan and Benefit Equalization Plan [Member] Hedge Fund Investments, Event Driven Fund [Member] Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2011 Defined Benefit Pension Plan and Benefit Equalization Plan [Member] Hedge Fund Investments, Event Driven Fund [Member] Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2012 Defined Benefit Pension Plan and Benefit Equalization Plan [Member] Hedge Funds, Distressed Credit [Member] Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2011 Defined Benefit Pension Plan and Benefit Equalization Plan [Member] Hedge Funds, Distressed Credit [Member] Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2012 Defined Benefit Pension Plan and Benefit Equalization Plan [Member] Hedge Fund Investments, Multi-Strategy Fund [Member] Significant Unobservable Inputs (Level 3) [Member]	Dec. 31, 2011 Defined Benefit Pension Plan and Benefit Equalization Plan [Member] Hedge Fund Investments, Multi-Strategy Fund [Member] Significant Unobservable Inputs (Level 3) [Member]
Change in Fair Value of Plan Assets [Abstract]
Balance at beginning of year	$ 66,137	$ 62,105	$ 21,653	$ 29,729	$ 19,818	$ 12,821	$ 9,992	$ 12,821	$ 13,694	$ 7,126	$ 7,152	$ 7,126	$ 5,388	$ 6,252	$ 2,559	$ 6,252	$ 2,839	$ 3,530	$ 1,950	$ 3,530	$ 66,137	$ 62,105	$ 61,702	$ 29,729	$ 35,096	$ 12,821	$ 12,864	$ 7,126	$ 8,444	$ 6,252	$ 9,447	$ 3,530	$ 4,341
Realized gains (losses)																								7	2,269	0	981	0	672	5	306	2	310
Unrealized gains (losses)																								2,684	(1,339)	1,624	(889)	522	(140)	365	(219)	173	(91)
Purchases																								9,392	7,933	5,555	7,884	3,798	26	20	7	19	16
Sales																								(1,667)	(14,230)	0	(8,019)	0	(1,876)	(894)	(3,289)	(773)	(1,046)
Transfer to Level 2																								(18,492)		(10,008)		(4,294)		(3,189)		(1,001)
Balance at end of year	$ 66,137	$ 62,105	$ 21,653	$ 29,729	$ 19,818	$ 12,821	$ 9,992	$ 12,821	$ 13,694	$ 7,126	$ 7,152	$ 7,126	$ 5,388	$ 6,252	$ 2,559	$ 6,252	$ 2,839	$ 3,530	$ 1,950	$ 3,530	$ 66,137	$ 62,105	$ 61,702	$ 21,653	$ 29,729	$ 9,992	$ 12,821	$ 7,152	$ 7,126	$ 2,559	$ 6,252	$ 1,950	$ 3,530