Nature of Operations and Summary of Significant Accounting Policies Other Investments (Details)
|
12 Months Ended |
Dec. 31, 2016 |
|---|
| Investment In Limited Partnerships Accounting Treatment [Line Items] |
|
| Maximum ownership percentage that is not consolidated |
50.00%
|
| Investment in corporations minimum ownership percentage for accounting for using the equity method |
20.00%
|
| Investment in corporations maximum ownership percentage for accounting for at cost |
20.00%
|
| Investment in limited partnerships maximum ownership percentage for accounting for at cost |
3.00%
|
| Minimum |
|
| Investment In Limited Partnerships Accounting Treatment [Line Items] |
|
| Investment in limited partnerships ownership percentage for accounting for using the equity method |
3.00%
|
| Maximum |
|
| Investment In Limited Partnerships Accounting Treatment [Line Items] |
|
| Investment in limited partnerships ownership percentage for accounting for using the equity method |
50.00%
|