Intangible Assets

Intangible assets consisted of the following:



	September 30, 2016		December 31, 2015
	(in millions)
Mortgage servicing rights	$	—	$	140
Purchased credit card relationships	36		41
Total intangible assets	$	36	$	181

Mortgage Servicing Rights ("MSRs") A servicing asset is a contract under which estimated future revenues from contractually specified cash flows, such as servicing fees and other ancillary revenues, are expected to exceed the obligation to service the financial assets. Prior to our agreement with PHH Mortgage, we recognized the right to service residential mortgage loans as a separate and distinct asset at the time they were acquired or when originated loans were sold.

In March 2016, we initiated an active program to sell our remaining MSRs portfolio and reclassified them to held for sale within other assets on the consolidated balance sheet. See Note 9, "Other Assets Held for Sale," for additional information on our MSRs portfolio at September 30, 2016 and during the three and nine months ended September 30, 2016.

The following table summarizes the critical assumptions used to calculate the fair value of MSRs at December 31, 2015:



	December 31, 2015
Annualized constant prepayment rate	13.8	%
Constant discount rate	12.6	%
Weighted average life (in years)	4.5

The following table summarizes MSRs activity during the three and nine months ended September 30, 2015:



	Three Months Ended September 30, 2015			Nine Months Ended September 30, 2015
	(in millions)
Fair value of MSRs:
Beginning balance	$	158		$	159
Changes in fair value due to changes in valuation inputs or assumptions	(21		)	(13		)
Reductions related to customer payments	(7		)	(16		)
Ending balance	$	130		$	130

The outstanding principal balance of serviced for others mortgages, which are not included in the consolidated balance sheet, totaled $18,930 million at December 31, 2015. Servicing fees collected are included in residential mortgage banking revenue (expense) and totaled $13 million and $43 million during the three and nine months ended September 30, 2015, respectively.

PHH Mortgage provides us with mortgage origination processing services as well as the sub-servicing of our portfolio of owned and serviced for others mortgages with an outstanding principal balance of $35,164 million and $37,544 million at September 30, 2016 and December 31, 2015, respectively. Although we continue to own both the mortgages on our balance sheet and the mortgage servicing rights associated with the serviced loans at the time of conversion, we sell our agency eligible originations to PHH Mortgage on a servicing released basis which results in no new mortgage servicing rights being recognized.

Purchased credit card relationships In 2012, we purchased from HSBC Finance the account relationships associated with $746 million of credit card receivables which were not included in the sale to Capital One Financial Corporation at a fair value of $108 million. Approximately $43 million of this value was associated with the credit card receivables sold to First Niagara Bank, National Association and was written off at the time of sale. The remaining $65 million was included in intangible assets and is being amortized over the estimated useful life of the credit card relationships which is ten years.