Reconciliation of Statutory Federal Income Tax Rate to Effective Income Tax Rate (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended	3 Months Ended	12 Months Ended
Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Rate Reconciliation [Line Items]
Expected federal income tax expense	$ 15,722
Dividends received deduction	(1,470)
Other	(18)
Total income tax expense	14,234us-gaap_IncomeTaxExpenseBenefit
Statutory federal income tax rate	35.00%
Predecessor
Income Tax Rate Reconciliation [Line Items]
Total income tax expense		$ 922	$ 3,825	$ 4,273
Statutory federal income tax rate		35.00%	35.00%	35.00%
Other		0.00%	0.00%	0.00%
Effective income tax rate		35.00%	35.00%	35.00%

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

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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Percentage 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 other adjustments.

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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 deduction for dividend.

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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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