Fair value measurements Fair Value Measurements on a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Fair value measurements on a recurring and nonrecurring basis
Available-for-sale investment securities, at fair value	$ 820,648	$ 550,394
Mortgage-related securities-FNMA, FHLMC and GNMA
Fair value measurements on a recurring and nonrecurring basis
Available-for-sale investment securities, at fair value	607,689	430,834
U.S. Treasury and federal agency obligations
Fair value measurements on a recurring and nonrecurring basis
Available-for-sale investment securities, at fair value	212,959
Fair value measurements on a recurring basis \| Level 1
Fair value measurements on a recurring and nonrecurring basis
Derivative liabilities	15	71
Fair value measurements on a recurring basis \| Level 1 \| Forward Contracts
Fair value measurements on a recurring and nonrecurring basis
Derivative liabilities	15	71
Fair value measurements on a recurring basis \| Level 2
Fair value measurements on a recurring and nonrecurring basis
Derivative assets	385	398
Derivative liabilities	15	43
Fair value measurements on a recurring basis \| Level 2 \| Interest Rate Lock Commitments
Fair value measurements on a recurring and nonrecurring basis
Derivative assets	384	393
Derivative liabilities	0	3
Fair value measurements on a recurring basis \| Level 2 \| Forward Contracts
Fair value measurements on a recurring and nonrecurring basis
Derivative assets	1	5
Derivative liabilities	15	40
Fair value measurements on a recurring basis \| Level 2 \| Other
Fair value measurements on a recurring and nonrecurring basis
Money market funds	10	10
Fair value measurements on a recurring basis \| Level 2 \| Bank
Fair value measurements on a recurring and nonrecurring basis
Available-for-sale investment securities, at fair value	820,648	550,394
Fair value measurements on a recurring basis \| Level 2 \| Bank \| Mortgage-related securities-FNMA, FHLMC and GNMA
Fair value measurements on a recurring and nonrecurring basis
Available-for-sale investment securities, at fair value	607,689	430,834
Fair value measurements on a recurring basis \| Level 2 \| Bank \| U.S. Treasury and federal agency obligations
Fair value measurements on a recurring and nonrecurring basis
Available-for-sale investment securities, at fair value	$ 212,959	$ 119,560

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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