Income Taxes

Income taxes are accounted for using the liability method under which deferred income taxes are recognized for the future tax effects of temporary differences between financial statement carrying amounts and the tax basis of existing assets and liabilities using the enacted statutory tax rates in effect at period-end. The effect on deferred taxes for a change in tax rates is recognized in income in the period that includes the enactment date. The Company’s policy is to recognize penalties and interest related to unrecognized tax benefits, if any, in income tax expense. A valuation allowance for deferred tax assets is recorded when it is more likely than not that the benefit from the deferred tax asset will not be realized.

The Company's (provision) for income taxes totaled ($97.5) million and ($6.8) million for the three months ended September 30, 2018 and 2017, respectively. The Company's (provision) benefit for income taxes totaled ($244.2) million and $25.1 million for the nine months ended September 30, 2018 and 2017, respectively. These amounts differ from the amounts computed by applying the United States statutory federal income tax rate to net income/loss before income taxes. The sources and tax effects of the differences are reflected in the table below:



	Three months ended September 30,										Nine months ended September 30,
$ in thousands	2018			Tax rate %		2017			Tax rate %		2018			Tax rate %		2017			Tax rate %
Expected income tax (provision) benefit based on US statutory tax rate (1)	$	(86,443	)	21	%	$	(6,087	)	35	%	$	(217,311	)	21	%	$	27,136		35	%
State income taxes, net of federal benefit	(12,349		)	3	%	(522		)	3	%	(31,044		)	3	%	2,326			3	%
Tax benefit (deficiency) from stock-based compensation	235			—	%	(134		)	1	%	2,103			—	%	(3,907		)	(5	%)
Canadian valuation allowance (2)	(51		)	—	%	(68		)	—	%	(198		)	—	%	(325		)	(1	%)
Other, net	1,142			—	%	41			—	%	2,216			—	%	(167		)	—	%
(Provision) benefit for income taxes	$	(97,466	)	24	%	$	(6,770	)	39	%	$	(244,234	)	24	%	$	25,063		32	%


(1)	In December 2017 the Tax Cuts and Jobs Act was signed into law, which among other things reduced the U.S. federal corporate income tax rate from 35% to 21% effective January 1, 2018.


(2)	Represents valuation allowances recognized against all deferred tax assets associated with operating loss carryforwards generated by the Company's Canadian operations during the respective periods for which the Company does not expect to realize a benefit.