Income Taxes	6 Months Ended
Jun. 30, 2017
Income Taxes [Abstract]
Income Taxes	9. Income Taxes Income Tax Expense Our effective income tax rate was 24% and 9% for the three and six months ended June 30, 2017, respectively, as compared to 39% and 51% for the three and six months ended June 30, 2016, respectively. Our income tax rate for the three and six months ended June 30, 2017 was favorably affected by excess tax benefits, primarily related to the exercise of non-qualified stock options and the vesting of stock awards, as discussed in Note 1 above, which decreased income tax expense by approximately $532,000 and $1.6 million, respectively. Our income tax rate for the three and six months ended June 30, 2016 was unfavorably impacted by the tax treatment of certain expenses related to the On-X acquisition, which had a larger impact on the tax rate in first quarter of 2016. Our income tax rate for the six months ended June 30, 2016 was also unfavorably impacted by book/tax basis differences related to the HeRO Sale. Deferred Income Taxes We generate deferred tax assets primarily as a result of write-downs of inventory and deferred preservation costs; accruals for product and tissue processing liability claims; investment and asset impairments; and, in prior periods, due to operating losses. We acquired significant deferred tax assets, primarily net operating loss carryforwards, from our acquisitions of On-X in 2016, Hemosphere in 2012, and Cardiogenesis in 2011. We recorded significant deferred tax liabilities in 2016 related to the intangible assets acquired in the On-X acquisition. As of June 30, 2017 we maintained a total of $2.2 million in valuation allowances against deferred tax assets, related to state net operating loss carryforwards, and had a net deferred tax asset of $148,000. As of December 31, 2016 we had a total of $2.2 million in valuation allowances against deferred tax assets, related to state net operating loss carryforwards, and a net deferred tax liability of $7,000.

9. Income Taxes

Income Tax Expense

Our effective income tax rate was 24% and 9% for the three and six months ended June 30, 2017, respectively, as compared to 39% and 51% for the three and six months ended June 30, 2016, respectively. Our income tax rate for the three and six months ended June 30, 2017 was favorably affected by excess tax benefits, primarily related to the exercise of non-qualified stock options and the vesting of stock awards, as discussed in Note 1 above, which decreased income tax expense by approximately $532,000 and $1.6 million, respectively.

Our income tax rate for the three and six months ended June 30, 2016 was unfavorably impacted by the tax treatment of certain expenses related to the On-X acquisition, which had a larger impact on the tax rate in first quarter of 2016. Our income tax rate for the six months ended June 30, 2016 was also unfavorably impacted by book/tax basis differences related to the HeRO Sale.

Deferred Income Taxes

We generate deferred tax assets primarily as a result of write-downs of inventory and deferred preservation costs; accruals for product and tissue processing liability claims; investment and asset impairments; and, in prior periods, due to operating losses. We acquired significant deferred tax assets, primarily net operating loss carryforwards, from our acquisitions of On-X in 2016, Hemosphere in 2012, and Cardiogenesis in 2011. We recorded significant deferred tax liabilities in 2016 related to the intangible assets acquired in the On-X acquisition.

As of June 30, 2017 we maintained a total of $2.2 million in valuation allowances against deferred tax assets, related to state net operating loss carryforwards, and had a net deferred tax asset of $148,000. As of December 31, 2016 we had a total of $2.2 million in valuation allowances against deferred tax assets, related to state net operating loss carryforwards, and a net deferred tax liability of $7,000.