Income Taxes - Reconciliation of The Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Income tax expense computed at statutory rate	$ 20,981	$ 46,538	$ 42,136
Increases (decreases) resulting from:
State income taxes, net of federal tax benefit	1,936	3,661	5,064
Federal jobs credits	(5,006)	(4,193)	(4,550)
Tax exempt interest	(384)	(568)	(457)
Share-based compensation, excess tax benefit	(1,179)	(4,632)	653
United States Tax Reform - remeasurement of deferred taxes	0	3,719	0
Other, net	38	214	145
Tax provision	$ 16,386	$ 44,739	$ 42,991

Effective Income Tax Rate Reconciliation, Increases (Decreases) [Abstract]

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Amount of difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying domestic federal statutory income tax rate to pretax income (loss) from continuing operation, attributable to excess tax benefit for share-based compensation cost.

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations, attributable to increase (decrease) in the income tax rates.

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The amount of income tax expense or benefit for the period computed by applying the domestic federal statutory tax rates to pretax income from continuing operations.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to noncontrolling interest income (loss) exempt from income taxes.

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