Exit activities (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Restructuring Cost and Reserve [Line Items]
Employee termination benefits	$ 165,024	$ 164,423	$ 498,598	$ 457,596
Accelerated depreciation of assets	7,633	$ 6,621	22,013	$ 16,070
Exit Plan Out Of Delinquent Loan Servicing Operations
Restructuring Cost and Reserve [Line Items]
Restructuring costs recorded	600
Employee Severance | Exit Plan Out Of Delinquent Loan Servicing Operations
Restructuring Cost and Reserve [Line Items]
Employee termination benefits	200
Accelerated Depreciation of Assets | Exit Plan Out Of Delinquent Loan Servicing Operations
Restructuring Cost and Reserve [Line Items]
Accelerated depreciation of assets	400
Minimum | Exit Plan Out Of Delinquent Loan Servicing Operations
Restructuring Cost and Reserve [Line Items]
Delinquent loan servicing exit, estimated total charge to be incurred	5,000		5,000
Maximum | Exit Plan Out Of Delinquent Loan Servicing Operations
Restructuring Cost and Reserve [Line Items]
Delinquent loan servicing exit, estimated total charge to be incurred	$ 7,000		$ 7,000