Income Tax (Tables)

3 Months Ended

Mar. 31, 2016

Income Tax Disclosure [Abstract]

Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]

Provision for income tax expense differed from the amounts computed by applying the U.S. federal income tax statutory rate of 35% to pre-tax income as a result of the following for the three months ended March 31, 2016 and 2015 (dollars in thousands):

	Three months ended March 31,
	2016			2015
Tax provision at U.S. statutory rate	$	37,653		$	64,444
Increase (decrease) in income taxes resulting from:
Foreign tax rate differing from U.S. tax rate	(3,884		)	(5,517		)
Differences in tax bases in foreign jurisdictions	(8,935		)	(6,670		)
Deferred tax valuation allowance	4,999			6,791
Amounts related to tax audit contingencies	602			952
Corporate rate changes	(65		)	272
Subpart F	696			6,434
Foreign tax credits	(293		)	(2,343		)
Return to provision adjustments	125			(4,765		)
Other, net	210			(587		)
Total provision for income taxes	$	31,108		$	59,011
Effective tax rate	28.9		%	32.0		%