Debt (Senior Notes Payable) - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended		12 Months Ended
	Jul. 31, 2013	Dec. 31, 2009	Mar. 31, 2015
Debt Instrument [Line Items]
Excess leverage fee outstanding			$ 500
Senior Notes Payable [Member]
Debt Instrument [Line Items]
Quarterly interest payable		5.60%
Senior notes		$ 75,000
Principal payment		25,000
Senior Notes Payable [Member] | ADS [Member]
Debt Instrument [Line Items]
Senior Notes	$ 25,000	$ 100,000
Quarterly interest payable	4.05%
Principal payment	$ 25,000
Debt instrument leverage fee			The rate is subject to an additional 200 basis point excess leverage fee if calculated leverage ratio exceeds 3 to 1 at the end of a fiscal quarter.