Summary of Changes in Accumulated Balances of AOCI Including Current Period Other Comprehensive Income (Loss) and Reclassifications Out of AOCI (Detail) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	[1]			$ 2,766,275
Other comprehensive income (loss) before reclassifications		$ (18,894)	$ 2,071	(21,527)	$ (14,086)
Less net gain (loss) reclassified from AOCI		695	(2,224)	6,463	5,397
Tax effect		(89)	186	516	2,978
Net current-period other comprehensive income (loss)		(19,678)	4,481	(27,474)	(16,505)
Ending Balance		2,795,579		2,795,579
Unrealized Gains (Losses) on Cash Flow Hedges
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance		6,291	(2,500)	13,006	13,602
Other comprehensive income (loss) before reclassifications		(19,165)	4,608	(23,364)	(3,873)
Less net gain (loss) reclassified from AOCI		695	(197)	3,211	7,424
Tax effect		0	0	0	0
Net current-period other comprehensive income (loss)		(19,860)	4,805	(26,575)	(11,297)
Ending Balance		(13,569)	2,305	(13,569)	2,305
Unrealized Gains (Losses) on Available-for-Sale Securities
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance		(1,258)	2,554	(178)	7,441
Other comprehensive income (loss) before reclassifications		267	(2,536)	1,834	(10,215)
Less net gain (loss) reclassified from AOCI		0	(2,027)	3,252	(2,027)
Tax effect		(89)	186	516	2,978
Net current-period other comprehensive income (loss)		178	(323)	(902)	(5,210)
Ending Balance		(1,080)	2,231	(1,080)	2,231
Foreign Currency Items
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance		(13)	(7)	(12)	(10)
Other comprehensive income (loss) before reclassifications		4	(1)	3	2
Less net gain (loss) reclassified from AOCI		0	0	0	0
Tax effect		0	0	0	0
Net current-period other comprehensive income (loss)		4	(1)	3	2
Ending Balance		(9)	(8)	(9)	(8)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance		5,020	47	12,816	21,033
Other comprehensive income (loss) before reclassifications		0	0	0	0
Less net gain (loss) reclassified from AOCI		0	0	0	0
Tax effect		0	0	0	0
Net current-period other comprehensive income (loss)		0	0	0	0
Ending Balance		$ (14,658)	$ 4,528	$ (14,658)	$ 4,528

[1] December 31, 2016 balances were derived from the audited Consolidated Financial Statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2016, filed with the Securities and Exchange Commission (the SEC) on February 27, 2017.