Benefit Plans and Other Postretirement Benefits, Changes in Level 3 Postretirement Benefit Plan Assets (Details) (Postretirement Benefit Plan, USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012	Dec. 31, 2011
Changes in Level 3 Plan Assets [Roll Forward]
Fair value of plan assets at Dec. 31	$ 746		$ 647	$ 746
Level 3
Changes in Level 3 Plan Assets [Roll Forward]
Fair value of plan assets at Jan. 1	55		62	51
Net realized gains (losses)	0		(1)	(3)
Net unrealized gains (losses)	0		9	4
Purchases, issuances and settlements, net	0		(15)	10
Transfers in (out) of Level 3	(55)	[1]	0	0
Fair value of plan assets at Dec. 31	0		55	62
Asset-backed securities
Changes in Level 3 Plan Assets [Roll Forward]
Fair value of plan assets at Dec. 31	5		1
Asset-backed securities | Level 3
Changes in Level 3 Plan Assets [Roll Forward]
Fair value of plan assets at Jan. 1	1		14	6
Net realized gains (losses)	0		0	0
Net unrealized gains (losses)	0		3	(2)
Purchases, issuances and settlements, net	0		(16)	10
Transfers in (out) of Level 3	(1)	[1]	0	0
Fair value of plan assets at Dec. 31	0		1	14
Mortgage-backed securities
Changes in Level 3 Plan Assets [Roll Forward]
Fair value of plan assets at Dec. 31	37		54
Mortgage-backed securities | Level 3
Changes in Level 3 Plan Assets [Roll Forward]
Fair value of plan assets at Jan. 1	54		48	45
Net realized gains (losses)	0		(1)	(3)
Net unrealized gains (losses)	0		6	6
Purchases, issuances and settlements, net	0		1	0
Transfers in (out) of Level 3	(54)	[1]	0	0
Fair value of plan assets at Dec. 31	$ 0		$ 54	$ 48

[1] Transfers out of Level 3 into Level 2 were principally due to diminished use of unobservable inputs that were previously significant to these fair value measurements and were subsequently sold during 2013.