Accumulated Other Comprehensive Income (Loss) - Summary of Changes in Accumulated Other Comprehensive Income (Loss) (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at December 31, 2013	$ (8,582)
Other comprehensive income (loss) before reclassifications	(4,569)
Amounts reclassified out of accumulated other comprehensive income (loss)	6,727
Other comprehensive income (loss)	2,158	11,381	1,527
Balance at December 31, 2014	(6,424)	(8,582)
Gains and Losses on Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at December 31, 2013	(8,859)
Other comprehensive income (loss) before reclassifications	(3,841)
Amounts reclassified out of accumulated other comprehensive income (loss)	6,727
Other comprehensive income (loss)	2,886
Balance at December 31, 2014	(5,973)
Defined Benefit Pension Plan [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at December 31, 2013	277
Other comprehensive income (loss) before reclassifications	(728)
Other comprehensive income (loss)	(728)
Balance at December 31, 2014	$ (451)