Commitments and Contingencies (Details) (USD $)	0 Months Ended		12 Months Ended
	Nov. 19, 2014	Sep. 12, 2014	Dec. 31, 2014 subsidiary	Dec. 31, 2013	Dec. 31, 2012	Jul. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Rent expense under operating leases			$ 12,500,000	$ 13,500,000	$ 11,100,000
Minimum sublease rentals due in the future			4,100,000
Principal balance of loans sold with recourse provisions			355,000,000	358,100,000
Number of indemnification protection expiration days		180 days
Numbers of deficiency cure days		90 days
Standby letters of credit, term extended by guarantee			1 year
Income tax examination, estimate of possible loss	6,100,000		13,300,000
Outstanding standby letters of credit			1,200,000	513,000
Income tax examination number of subsidiaries			2
Residential mortgage loans | Non-performing loans held-for-sale, net
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value, loans sold		4,000,000				$ 173,700,000