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Accounting Pronouncements (Details) - USD ($) $ in Thousands | 6 Months Ended
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Jun. 30, 2018 | Jun. 30, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |
Undistributed gains of equity method investments | $ (1,628) | $ (3,584)
Distributions in excess of current year income of equity method investments | 1,450 | 552
Decrease (increase) in other assets | (6,550) | (3,862)
Net cash provided by operating activities | 92,257 | 95,451
Distributions from other investments | 15,927 | 9,300
Net cash used in investing activities | (96,402) | (94,017)
Scenario, Previously Reported [Member] |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |
Undistributed gains of equity method investments |  | (3,575)
Distributions in excess of current year income of equity method investments |  | 0
Decrease (increase) in other assets |  | 24,953
Net cash provided by operating activities |  | 123,723
Distributions from other investments |  | 9,843
Net cash used in investing activities |  | (93,474)
AOCI Attributable to Parent [Member] |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |
Cumulative effect of new accounting principle in period of adoption | (25,019) |
AOCI Attributable to Parent [Member] | Accounting Standards Update 2016-01 [Member] |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |
Cumulative effect of new accounting principle in period of adoption | (30,726) | 0
AOCI Attributable to Parent [Member] | Accounting Standards Update 2018-02 [Member] |  |
New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |
Cumulative effect of new accounting principle in period of adoption | $ 5,707 | $ 0

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