Selling, general and administrative ("SG&A") expense includes $37.6 million, $57.3 million, $51.6 million, $47.0 million and $265.9 million for the years ended December 31, 2014, 2013, 2012, 2011, and 2010, respectively, of aggregate costs related to the resolution of the previously disclosed governmental and Company investigations, such as settlement accruals and related fair value accretion, legal fees and other similar costs. The 2010 costs are net of $25.8 million of D&O insurance recoveries related to the consolidated securities class action during this period.
The ACA imposed certain new taxes and fees, including limitations on the amount of compensation that is tax deductible, as well as an annual premium-based health insurance industry assessment (the "ACA industry fee") on health insurers which began in 2014. The total ACA industry fee levied on the health insurance industry was $8 billion in 2014 and
Interest expense for the year ended December 31, 2014 was $39.4 million compared to $11.9 million for the same period in 2013. The $27.5 million increase was primarily driven by higher average debt levels during 2014, as we borrowed an additional $300 million term loan (the "Term Loan") under the current credit agreement in September 2014 and, additionally, issued $600 million of 5.75% senior notes (the "Senior Notes") in November 2013.
Based on the outcome of our 2014 stand-alone PDP bids, our plans were below the benchmarks in 30 of the 33 CMS regions for which we submitted bids and within the de minimis range of the benchmark in two other CMS regions. Comparatively, in 2013, our plans were below the benchmark in 14 regions and within the de minimis range in five other regions. In 2014, we were auto-assigned newly eligible members into our plans for the 30 regions that were below the benchmark. Membership increased to approximately 1,392,000 at December 31, 2014, compared to 797,000 at December 31, 2013.
We anticipate that PDP segment premium revenue will decrease to approximately $1.0 to $1.1 billion in 2015, primarily as a result of a decline in membership resulting from the outcome of our 2015 bids, as discussed below.
Each of our existing and anticipated sources of cash is impacted by operational and financial risks that influence the overall amount of cash generated and the capital available to us. Additionally, we operate as a holding company in a highly regulated industry. The parent and other non-regulated companies ("non-regulated subsidiaries") are dependent upon dividends and management fees from our regulated subsidiaries, most of which are subject to regulatory restrictions. For a further discussion of risks that can affect our liquidity, see Part I - Item 1A - Risk Factors included in this 2014 Form 10-K.
We generally receive premiums in advance of payments of claims for health care services; however, cash flows related to our operations can fluctuate significantly in a particular period depending on the timing of premiums receipts from our government partners or payments related to the resolution of government investigations and related litigation.
Net cash used in investing activities for 2014 was $75.6 million compared to $290.5 million for 2013. The decrease in cash used in 2014 primarily resulted from a higher amount of cash used in acquisitions in 2013 relative to 2014, including $133.6 million advanced in December 2013 in connection with the Windsor acquisition, which closed in January 2014. Conversely, in 2014 cash flows reflect $48.0 million of net cash acquired from acquisitions. Excluding acquisitions, investment activities primarily reflect our investment in marketable securities and restricted investments, purchases of property and equipment and proceeds from maturities of marketable securities and restricted investments, which in combination, did not materially change year over year.
Low-Income Cost Sharing Subsidy (LICS)- For qualifying low income members, CMS reimburses us for all or a portion of the low income member's deductible, coinsurance and co-payment amounts above the out-of-pocket threshold.
Medical benefits payable recorded at December 31, 2014, 2013 and 2012 developed favorably by approximately $26.2 million, $74.6 million and $146.6 million in 2014, 2013 and 2012, respectively. A portion of the prior period development was