Income Taxes

The following table presents income tax expense and the effective tax rate:



	Three Months Ended March 31,
	2016			2015
	(Dollars in thousands)
Income tax expense	$	33,628		$	28,427
Effective tax rate	24		%	24		%

The effective tax rate for the three months ended March 31, 2016 and 2015 is lower than the statutory federal rate of 35% primarily due to tax benefits from foreign income taxed at lower rates, partially offset by state income taxes.

Deferred tax liabilities as of March 31, 2016 reflect the use of a portion of U.S. foreign tax credits during the three months ended March 31, 2016, and an increase in the deferred tax liability related to the Subordinated Convertible Debentures.