Accumulated Other Comprehensive Income , Equity and Redeemable Noncontrolling Interests - Summary of Equity and Redeemable Noncontrolling Interest Activity (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Equity And Noncontrolling Interests [Line Items]
Equity at January 1, 2015	$ 548,714
Net Income (Loss) Attributable to Parent	20,987	19,735
Net income (loss)	21,128	21,357
Warrant exercise	0	4,571
Equity at March 31, 2015	541,924
Total [Member]
Equity And Noncontrolling Interests [Line Items]
Equity at January 1, 2015	548,714
Net income (loss)	21,173
Warrant exercise	24
Other comprehensive income (loss)	(43,884)
Stock-based compensation, net	1,546
Acquisition of Shenya	11,368
Shares issued under stock option plans	(71)
Purchase of noncontrolling interest	3,054
Equity at March 31, 2015	541,924
Parent [Member]
Equity And Noncontrolling Interests [Line Items]
Equity at January 1, 2015	548,966
Net income (loss)	20,987
Warrant exercise	24
Other comprehensive income (loss)	(43,993)
Stock-based compensation, net	1,546
Acquisition of Shenya	0
Shares issued under stock option plans	(71)
Purchase of noncontrolling interest	2,862
Equity at March 31, 2015	530,321
Noncontrolling Interest [Member]
Equity And Noncontrolling Interests [Line Items]
Equity at January 1, 2015	(252)
Net income (loss)	186
Warrant exercise	0
Other comprehensive income (loss)	109
Stock-based compensation, net	0
Acquisition of Shenya	11,368
Shares issued under stock option plans	0
Purchase of noncontrolling interest	192
Equity at March 31, 2015	11,603
Redeemable Noncontrolling Interests [Member]
Equity And Noncontrolling Interests [Line Items]
Equity at January 1, 2015	3,981
Net income (loss)	(45)
Warrant exercise	0
Other comprehensive income (loss)	0
Stock-based compensation, net	0
Acquisition of Shenya	0
Shares issued under stock option plans	0
Purchase of noncontrolling interest	(3,936)
Equity at March 31, 2015	$ 0