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	$ 136,546	$ 121,348	$ 123,541
Level 3 [Member]
Changes in Level 3 Plan Assets [Roll Forward]
Fair value of plan assets at Jan. 1	15,807	17,801	16,984
Net realized gains (losses)	1,236	352	823
Net unrealized gains (losses)	(1,254)	1,230	240
Purchases, issuances and settlements, net	(895)	(3,576)	(246)
Fair value of plan assets at Dec. 31	14,894	15,807	17,801
Asset-backed Securities [Member]
Changes in Level 3 Plan Assets [Roll Forward]
Fair value of plan assets at Dec. 31	749	1,578
Asset-backed Securities [Member] | Level 3 [Member]
Changes in Level 3 Plan Assets [Roll Forward]
Fair value of plan assets at Jan. 1	1,578	1,367	2,357
Net realized gains (losses)	197	121	173
Net unrealized gains (losses)	(273)	(125)	(140)
Purchases, issuances and settlements, net	(753)	215	(1,023)
Fair value of plan assets at Dec. 31	749	1,578	1,367
Mortgage-backed Securities [Member]
Changes in Level 3 Plan Assets [Roll Forward]
Fair value of plan assets at Dec. 31	2,128	3,781
Mortgage-backed Securities [Member] | Level 3 [Member]
Changes in Level 3 Plan Assets [Roll Forward]
Fair value of plan assets at Jan. 1	3,781	5,984	7,280
Net realized gains (losses)	93	55	707
Net unrealized gains (losses)	(112)	(295)	(717)
Purchases, issuances and settlements, net	(1,634)	(1,963)	(1,286)
Fair value of plan assets at Dec. 31	2,128	3,781	5,984
Private Equity Investments [Member]
Changes in Level 3 Plan Assets [Roll Forward]
Fair value of plan assets at Dec. 31	8,545	8,440
Private Equity Investments [Member] | Level 3 [Member]
Changes in Level 3 Plan Assets [Roll Forward]
Fair value of plan assets at Jan. 1	8,440	6,704	4,053
Net realized gains (losses)	945	210	(55)
Net unrealized gains (losses)	(1,197)	648	809
Purchases, issuances and settlements, net	357	878	1,897
Fair value of plan assets at Dec. 31	8,545	8,440	6,704
Real Estate [Member]
Changes in Level 3 Plan Assets [Roll Forward]
Fair value of plan assets at Dec. 31	3,472	2,008
Real Estate [Member] | Level 3 [Member]
Changes in Level 3 Plan Assets [Roll Forward]
Fair value of plan assets at Jan. 1	2,008	3,746	3,294
Net realized gains (losses)	1	(34)	(2)
Net unrealized gains (losses)	328	1,002	288
Purchases, issuances and settlements, net	1,135	(2,706)	166
Fair value of plan assets at Dec. 31	$ 3,472	$ 2,008	$ 3,746