Medical Cost Trends. Our medical cost trends primarily relate to changes in unit costs, health system utilization and prescription drug costs. Consistent with our experience in recent years, our 2015 cost trends were largely driven by unit cost pressures from health care providers. In 2016, we expect continued unit cost pressure and a modest increase in utilization. We endeavor to mitigate those increases with medical management. Our 2016 management activities include managing costs across all health care categories, including specialty pharmacy spending, as new therapies are introduced at high costs and older drugs have unexpected price increases.
UnitedHealthcare grew to serve an additional 1.7 million people domestically. Each Optum business grew revenues by 19% or more.
Earnings from operations and operating margins for the year ended December 31, 2014 increased primarily due to growth in scale that resulted in greater productivity and better absorption of our fixed costs and improved performance in both drug purchasing and home delivery pharmacy fulfillment.
Other significant changes in sources or uses of cash year-over-year included: (a) a change in investment activity from net purchases in 2013 to net sales in 2014; (b) an increase in Part D subsidy receivables causing a change in customer funds administered; and (c) increased levels of cash used to repurchase common stock.
variables such as gross-domestic product growth, employment and disposable income. A large number of factors can cause the medical cost trend to vary from our estimates, including: our ability and practices to manage medical and pharmaceutical costs, changes in level and mix of services utilized, mix of benefits offered, including the impact of co-pays and deductibles, changes in medical practices, catastrophes and epidemics.
During 2015, the Company changed its annual quantitative goodwill impairment testing date from January 1 to October 1 of each year. The change in the goodwill impairment test date better aligns the impairment testing procedures with the timing of the Company’s long-term planning process, which is a significant input to the testing. This change in testing date did not delay, accelerate, or avoid a goodwill impairment charge.
Valuation allowances are provided when it is considered more likely than not that deferred tax assets will not be realized. The valuation allowances primarily relate to future tax benefits on certain federal, state and non-U.S. net operating loss carryforwards. Federal net operating loss carryforwards of $122 million expire beginning in 2021 through 2035; state net operating loss carryforwards expire beginning in 2016 through 2035. Substantially all of the non-U.S. tax loss carryforwards have indefinite carryforward periods.
For the year ended December 31, 2015, the Company’s regulated subsidiaries paid their parent companies dividends of $4.4 billion, including $1.5 billion of extraordinary dividends. For the year ended December 31, 2014, the Company’s regulated subsidiaries paid their parent companies dividends of $4.6 billion, including $1.5 billion of extraordinary dividends. As of December 31, 2015, $286 million of the Company’s $10.9 billion of cash and cash equivalents was available for general corporate use.