Fair value - pension level 3 (Details 10) (Fair value, measurements using significant unobservable inputs (Level 3), Pension Benefits, USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Defined Benefit Plan Disclosure [Line Items]
Balance at beginning of year		$ 694
Total realized/unrealized losses		(261)
Purchases, issuances and settlements (net)		(144)
Balance at end of year		289
Corporate debt securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Balance at beginning of year	289	0
Total realized/unrealized losses	(47)	(2)
Purchases, issuances and settlements (net)	(242)	291
Balance at end of year	0	289
Collateral held on loaned securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Balance at beginning of year		694
Total realized/unrealized losses		(259)
Purchases, issuances and settlements (net)		(435)
Balance at end of year		$ 0