Commitments and Contingencies Contractual commitments (Details) (USD $)
In Thousands, unless otherwise specified |
12 Months Ended | |
---|---|---|
Dec. 31, 2014
|
Dec. 31, 2013
|
|
Affordable Housing Project Investment [Member] | ||
Long-term Purchase Commitment [Line Items] | ||
Contractual obligation | $ 4,556 | $ 2,727 |
Coralville, Iowa [Member] | Building Construction [Member] | ||
Long-term Purchase Commitment [Line Items] | ||
Payments for construction in process | 2,870 | |
Contractual obligation | $ 3,287 |