Commitments and Contingencies Certain Leasing Transactions. As described in Note 12 , " Long-Term Debt ," we entered into certain leasing transactions that have been classified as lease financing obligations. Such leases have initial terms that range from 16.5 years to 25 years . Additionally, the leases provide for renewal options ranging from 10 years to 25 years in aggregate. Operating Leases. We lease administrative and clinic facilities and certain equipment under non-cancelable operating leases expiring at various dates through 2023. Facility lease terms generally range from five to 10 years with one to two renewal options for extended terms. In most cases, we are required to make additional payments under facility operating leases for taxes, insurance and other operating expenses incurred during the lease period. Certain of our leases contain rent escalation clauses or lease incentives, including rent abatements and tenant improvement allowances. Rent escalation clauses and lease incentives are taken into account in determining total rent expense to be recognized during the lease term. Future minimum lease payments by year and in the aggregate under all operating leases and lease financing obligations consist of the following approximate amounts: Lease Financing Obligations Lease Financing Obligations - Related Party Operating Leases Total (In thousands) 2015 $ 11,397 $ 5,346 $ 29,142 $ 45,885 2016 11,739 5,528 22,989 40,256 2017 12,091 5,715 21,602 39,408 2018 12,454 5,910 20,296 38,660 2019 12,828 6,111 12,777 31,716 Thereafter 320,447 73,784 15,229 409,460 $ 380,956 $ 102,394 $ 122,035 $ 605,385 Rental expense related to operating leases amounted to $32.4 million , $24.5 million , and $20.5 million for the years ended December 31, 2014 , 2013 , and 2012 , respectively. The amounts reported in "Lease Financing Obligations," and "Lease Financing Obligations - Related Party," above represent our contractual lease commitments for the properties described in Note 12 , " Long-Term Debt " under the subheading