Benefit Plans and Other Postretirement Benefits, Changes in Level 3 Pension Plan Assets (Details) (Pension Plans [Member], USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Changes in Level 3 Plan Assets [Roll Forward]
Fair value of plan assets at Dec. 31	$ 376,138	$ 350,054	$ 337,421
Level 3 [Member]
Changes in Level 3 Plan Assets [Roll Forward]
Fair value of plan assets at Jan. 1	31,670	36,106	43,493
Net realized gains (losses)	2,664	838	1,959
Net unrealized gains (losses)	(2,751)	3,211	8,711
Purchases, issuances and settlements, net	(1,479)	(8,485)	(18,057)
Fair value of plan assets at Dec. 31	30,104	31,670	36,106
Asset-backed Securities [Member]
Changes in Level 3 Plan Assets [Roll Forward]
Fair value of plan assets at Dec. 31	1,755	4,018
Asset-backed Securities [Member] | Level 3 [Member]
Changes in Level 3 Plan Assets [Roll Forward]
Fair value of plan assets at Jan. 1	4,018	3,450	6,563
Net realized gains (losses)	531	328	466
Net unrealized gains (losses)	(741)	(355)	(378)
Purchases, issuances and settlements, net	(2,053)	595	(3,201)
Fair value of plan assets at Dec. 31	1,755	4,018	3,450
Mortgage-backed Securities [Member]
Changes in Level 3 Plan Assets [Roll Forward]
Fair value of plan assets at Dec. 31	4,331	7,907
Mortgage-backed Securities [Member] | Level 3 [Member]
Changes in Level 3 Plan Assets [Roll Forward]
Fair value of plan assets at Jan. 1	7,907	11,060	16,444
Net realized gains (losses)	245	170	1,744
Net unrealized gains (losses)	(265)	(865)	(1,732)
Purchases, issuances and settlements, net	(3,556)	(2,458)	(5,396)
Fair value of plan assets at Dec. 31	4,331	7,907	11,060
Private Equity Investments [Member]
Changes in Level 3 Plan Assets [Roll Forward]
Fair value of plan assets at Dec. 31	17,049	16,159
Private Equity Investments [Member] | Level 3 [Member]
Changes in Level 3 Plan Assets [Roll Forward]
Fair value of plan assets at Jan. 1	16,159	11,464	11,303
Net realized gains (losses)	1,886	401	(95)
Net unrealized gains (losses)	(2,296)	1,300	9,703
Purchases, issuances and settlements, net	1,300	2,994	(9,447)
Fair value of plan assets at Dec. 31	17,049	16,159	11,464
Real Estate [Member]
Changes in Level 3 Plan Assets [Roll Forward]
Fair value of plan assets at Dec. 31	6,969	3,586
Real Estate [Member] | Level 3 [Member]
Changes in Level 3 Plan Assets [Roll Forward]
Fair value of plan assets at Jan. 1	3,586	10,132	9,183
Net realized gains (losses)	2	(61)	(156)
Net unrealized gains (losses)	551	3,131	1,118
Purchases, issuances and settlements, net	2,830	(9,616)	(13)
Fair value of plan assets at Dec. 31	$ 6,969	$ 3,586	$ 10,132