Long-Term Obligations - Subordinated Notes (Detail) - Senior Notes [Member]	12 Months Ended
	Dec. 31, 2016
2021 Senior Secured Notes [Member] | Debt Instrument, Redemption, Period One [Member]
Schedule Of Carrying Amount Of Senior Notes [Line Items]
Debt instrument redemption period start date	Jul. 15, 2018
Debt instrument redemption price percentage	102.375%
2021 Senior Secured Notes [Member] | Debt Instrument, Redemption, Period Two [Member]
Schedule Of Carrying Amount Of Senior Notes [Line Items]
Debt instrument redemption period start date	Jul. 15, 2019
Debt instrument redemption price percentage	101.188%
2021 Senior Secured Notes [Member] | Debt Instrument, Redemption, Period Three [Member]
Schedule Of Carrying Amount Of Senior Notes [Line Items]
Debt instrument redemption price percentage	100.00%
2021 Senior Secured Notes [Member] | Debt Instrument, Redemption, Period Three [Member] | Later Than [Member]
Schedule Of Carrying Amount Of Senior Notes [Line Items]
Debt instrument redemption period start date	Jul. 15, 2020
2022 Senior Notes [Member] | Debt Instrument, Redemption, Period One [Member]
Schedule Of Carrying Amount Of Senior Notes [Line Items]
Debt instrument redemption period start date	Jul. 15, 2017
Debt instrument redemption price percentage	104.031%
2022 Senior Notes [Member] | Debt Instrument, Redemption, Period Two [Member]
Schedule Of Carrying Amount Of Senior Notes [Line Items]
Debt instrument redemption period start date	Jul. 15, 2018
Debt instrument redemption price percentage	102.688%
2022 Senior Notes [Member] | Debt Instrument, Redemption, Period Three [Member]
Schedule Of Carrying Amount Of Senior Notes [Line Items]
Debt instrument redemption period start date	Jul. 15, 2019
Debt instrument redemption price percentage	101.344%
2022 Senior Notes [Member] | Debt Instrument, Redemption, Period Four [Member]
Schedule Of Carrying Amount Of Senior Notes [Line Items]
Debt instrument redemption price percentage	100.00%
2022 Senior Notes [Member] | Debt Instrument, Redemption, Period Four [Member] | Later Than [Member]
Schedule Of Carrying Amount Of Senior Notes [Line Items]
Debt instrument redemption period start date	Jul. 15, 2020