Shareholders' Equity - Cumulative Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2018
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance beginning	$ 1,778,968	$ 1,330,043	$ 935,004
Adjusted balance				$ 1,330,755
Other comprehensive income before reclassifications	(110)	(3)	33,504
Amounts reclassified from cumulative other comprehensive income to net income	(196)	(37)	(34)
Other comprehensive income (loss)	(306)	(40)	33,470
Balance ending	1,705,754	1,778,968	1,330,043
Cumulative Other Comprehensive Income (Loss)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance beginning	106	60,427	26,957
Amounts reclassified from cumulative other comprehensive income to retained earnings				(60,281)
Adjusted balance				146
Amounts reclassified from cumulative other comprehensive income to net income	(196)
Balance ending	(200)	106	60,427
Unrealized Gain on Investment in Equity Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance beginning	0	45,116	21,074
Amounts reclassified from cumulative other comprehensive income to retained earnings				(45,116)
Adjusted balance				0
Other comprehensive income before reclassifications			24,042
Other comprehensive income (loss)			24,042
Balance ending	0	0	45,116
Equity in Unrealized Gains (Losses) of Investees
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance beginning	106	15,311	5,883
Amounts reclassified from cumulative other comprehensive income to retained earnings				(15,165)
Adjusted balance				146
Other comprehensive income before reclassifications	90	(3)	9,462
Amounts reclassified from cumulative other comprehensive income to net income	(196)	(37)	(34)
Other comprehensive income (loss)	(106)	(40)	9,428
Balance ending	0	106	15,311
Unrealized Loss on Financial Instrument
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance beginning	0	0	0
Adjusted balance				$ 0
Other comprehensive income (loss)		0
Balance ending		$ 0	$ 0
Unrealized Loss on Financial Instrument
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive income before reclassifications	(200)
Other comprehensive income (loss)	(200)
Balance ending	$ (200)

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount after tax of increase (decrease) to equity or (increase) decrease to net assets, resulting from the cumulative effect adjustment of a new accounting principle applied in the period of adoption.

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Amount after tax, before reclassification adjustments, of other comprehensive income (loss), attributable to parent.

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Amount after tax of other comprehensive income (loss) attributable to parent entity.

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Amount after tax of reclassification adjustments of other comprehensive income (loss) attributable to parent.

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Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

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Amount of stockholders' equity including the portion attributable to noncontrolling interests, after the cumulative effect adjustment of a new accounting principle applied in the period of adoption.

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