Segments Reconciliation (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reconciliation From Segment Totals To Consolidated Abstract
Operating income for reportable segments	$ 149,024				$ 142,500				$ 149,024	$ 142,500	$ 126,971
Non-operating Charges									(67,110)	(67,145)	(59,983)
Depreciation of corporate assets and amortization									(4,558)	(4,112)	(3,764)
Operating income	16,485	20,553	20,945	19,373	15,232	18,807	19,793	17,411	77,356	71,243	63,224
Interest expense									(2,371)	(2,922)	(4,283)
Interest income									2,541	986	592
Other income, net									767	3,519	3,415
Income before taxes and equity in net income of associated companies									$ 78,293	$ 72,826	$ 62,948