Income Tax (Tables)

3 Months Ended

Mar. 31, 2017

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, 2017 and 2016 (dollars in thousands):

	Three months ended March 31,
	2017			2016
Tax provision at U.S. statutory rate	$	72,745		$	37,653
Increase (decrease) in income taxes resulting from:
Foreign tax rate differing from U.S. tax rate	(6,153		)	(3,884		)
Differences in tax bases in foreign jurisdictions	(3,383		)	(8,935		)
Deferred tax valuation allowance	1,182			4,999
Amounts related to tax audit contingencies	611			602
Corporate rate changes	(1,237		)	(65		)
Subpart F	186			696
Foreign tax credits	(126		)	(293		)
Return to provision adjustments	229			125
Equity compensation excess benefit	(1,856		)	—
Other, net	134			210
Total provision for income taxes	$	62,332		$	31,108
Effective tax rate	30.0		%	28.9		%