Bank Credit Agreements and Other Short-Term and Long-Term Debt (Bank Credit Agreement) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Line of Credit Facility [Line Items]
Lines of credit maximum borrowing capacity	$ 67,173
Lines of credit amount outstanding	8,000	0
Unsecured [Member]
Line of Credit Facility [Line Items]
Lines of credit maximum borrowing capacity	47,173
Debt Instrument, Interest Rate Terms	Unsecured, interest at LIBOR plus margin, due quarterly
Lines of credit amount outstanding	0	0
Secured [Member]
Line of Credit Facility [Line Items]
Lines of credit maximum borrowing capacity	10,000
Debt Instrument, Interest Rate Terms	Secured, interest at LIBOR plus margin, due monthly (Revolver)
Lines of credit amount outstanding	8,000	0
Secured Uncommitted [Member]
Line of Credit Facility [Line Items]
Lines of credit maximum borrowing capacity	10,000
Debt Instrument, Interest Rate Terms	Secured, uncommitted, interest at LIBOR plus margin, due monthly (Uncommitted Facility)
Lines of credit amount outstanding	$ 0	$ 0